[Geography] Structure of Mystara

[Gawain_VIII]

Structure of MYSTARA
Like most worlds, Mystara has an exterior surface which faces the sun and the stars. But instead of being solid all the way to its core, the planet is hollow inside (see the diagram on page X). That interior is a world of its own—a world lit by a magical sun.
Two tubular polar openings allow access from Mystara’s surface to the Hollow World. Perpetually stormy weather (caused by the meeting of weather patterns from the two worlds’ different climates), deadly cold, and an anti-magic effect that renders magical items and spells useless prevent most travelers from crossing through these openings.
Two other structural peculiarities distinguish Mystara from real-world planets. Mystara’s World-shield is a layer of super-dense molten lava within the planetary crust. It provides gravity for both the outer and the Hollow World. Mystara’s Skyshield is a natural energy field that restrains the atmosphere to a fifteen-mile thick mantle over the outer and inner surfaces of the world. These phenomena are described more fully below.

[Gawain_VIII]

Measurements
Mystara is 7,926 miles in diameter. Its circumference at the equator is just over 24,860 miles. The planet’s crust averages about 1,200 miles thick when measured from the surface to the World-shield on either side, and its two tubular polar openings measure 1,500 miles in diameter at Mystara’s outer surface. Their curvature toward the Hollow World is so gradual as to be unnoticeable except from high in the air. The total surface area of the planet’s outer world, minus the polar openings, is just under 313 million square miles. Water covers 70% of the planet’s outer surface.
The interior diameter of Mystara is thus 3,790 miles (measured from any point on the Hollow World’s surface through the center of its floating sun and to the corresponding point on the opposite side of the Hollow World). The interior circumference of the Hollow World at the equator is 11,908 miles. The two polar openings are only 1,000 miles in diameter where they open into the Hollow World. The Hollow World has a surface area of just over 38 million square miles (minus the two polar openings) and 70 percent of the world is covered by water.

[Gawain_VIII]

The Worldshield
Although Mystara is hollow, its gravity is the same as our Earth. This is due to a layer of magical molten rock that runs through the center of Mystara’s crust. Called the World-shield by the Immortals, this layer of lava produces a gravitational field that pulls things toward it from both sides. Thus, on the interior surface of the Hollow World, “up” is towards the internal sun and “down” is towards the World-shield.
Not all of the World-shield is molten. The lava has hot spots and cool spots, and in some areas it’s solidified. There are even a few spots where the World-shield remains solid all the way through Mystara’s mantle. Natural tunnels and caves—and a few artificial passages and mines—can penetrate the World-shield in these areas. Tunnels through this solidified lava can provide access between the Hollow World and Mystara’s outer surface. Gravity tends to work in strange ways in these areas, though. “Up” and “down” are erratic at best, shifting with the slow movements of the still-molten World-shield that surrounds the cooler, solid areas.
The World-shield is strongly anti-magical. Mortal magic generally does not work within three hundred miles of the lava layer. (There are fluctuations in this effect, but they tend to be localized and temporary.) This anti-magic effect extends across both polar openings in a band 600 miles thick.

[Gawain_VIII]

The Skyshield
In the Prime Material Plane where Mystara is located, most worlds with atmospheres also have Skyshields. These natural bubbles of transparent energy make it difficult for anything—including air—to pass into the void that surrounds them. (There is no similar resistance to objects passing the other way, from space into the atmosphere.)
Mystara’s Skyshield is about 80,000 feet up. Small objects—up to roughly horse-sized—can exit the Skyshield with little difficulty. Larger objects attempting to exit are slowly deflected as they get near.
Occasionally, the Skyshield temporarily develops a rip or tear. This may be caused by the passage of objects (meteors, for example) or by natural but unexplained fluctuations in the Skyshield’s strength. Whenever a tear occurs, atmosphere escapes into the void with incredible force. The stream of air creates a freak tornado, known as a ripstorm, whirlhole, or Vortigern Vortex (after the Alphatian wizard who first studied the phenomenon).
In clear skies, these vortexes appear as shimmering, dancing funnels which extend up as far as the eye can see. In cloudy skies, they suck the clouds directly beneath the tear into a ferociously whirling spiral up to the edge of the atmosphere. Certain brave adventurers have learned how to ride these ripstorms up and out through the Skyshield.
Rips in the Skyshield are temporary and are not dangerous—except to objects caught in the whirling winds. The Skyshield repairs itself, “healing” 100 square feet of tear (a 10’×10’ hole) each round.

[Gawain_VIII]

The Atmosphere
Mystara’s atmosphere blankets the surface of both the outer and inner worlds and extends up to 80,000 feet. Unlike atmospheres in the real universe, Mystara’s atmosphere maintains the same pressure from sea level to the Skyshield. The oxygen level drops dramatically with altitude, however. Breathing becomes difficult at 15,000 feet and higher.
Characters above 15,000 feet (on a high mountain, riding a dragon, or whatever) are subject to altitude sickness (see PH Glossary, “sickened”). Above 20,000’ altitude, oxygen-breathing characters and creatures begin to suffocate (see DMG Chapter 8, “Suffocation”). Special breathing gear, magical items, or spells such as create air and survival (created by Alphatian mages for use in their skyships) can help keep characters alive above 20,000 feet.
There is no atmosphere beyond the Skyshield—either around Mystara or within the Hollow World. Unprotected characters caught in the airless void are considered to be holding their breath from the time they leave the atmosphere. Even if they can survive the lack of air, characters exposed to the void beyond Mystara for more than ten minutes must make a Fortitude save (see DMG Chapter 8, “Cold Dangers”). Within the Hollow World, the void is merely pleasantly cool.

[Gawain_VIII]

The Moons
Two moons circle the world of Mystara, but most inhabitants of Mystara only know about one of them.
The known moon is called Matera. It is a lifeless, silvery, crater-marked satellite. Matera waxes and wanes in a predictable pattern, controls the tides, and is a boon to nighttime predators and an inspiration to lovers.
The unknown moon is called Patera by the Immortals. It is not well known to the mortals of Mystara because it is small, magical, and invisible. It is also inhabited (see the entry for Myoshima in the “Geographic Overview” later in this chapter).

[Big Mac]

Great stuff.

I've got a couple of comments and "nit picks" that you may wish to consider.

EDIT: Wow, this turned out to be a lot of "nit picks", mostly down the SRD being all over the place about a couple of things.

Generally, I am not a fan of TSR's habit of putting their trademarks into ALLCAPS. It seems to be some sort of legal thing, rather than something designed for readability. I would much rather see Mystara, Mystara or even Mystara than MYSTARA.

Structure of MYSTARA
Like most worlds, MYSTARA has an exterior surface which faces the sun and the stars. But instead of being solid all the way to its core, the planet is hollow inside (see the diagram on page X).

"page X" - With the "page X" thing, someone is going to need to typeset the entire Mystara Campaign Setting, to place everything in the right place before you can work out the pages of all the "page X" placeholders. Then you are going to need to have people go through the thing and hunt down all the "page X"s and replace them with the right pages. I have heard of a few commercial products going to the press with a few placeholders left in them. Margaret Weis Press dropped the ball with at least one of the Dragonlance books.

IIRC there are some gamebooks that now follow a trend of calling things Diagram 1, Diagram 2, Diagram 3,...Diagram 198, etc. Either way is valid, but I think that if you had a "Diagram X" placeholder, it could be swapped for the correct diagram number at a much earlier point. In fact, if the diagram numbers, table numbers, sidebar numbers and any other numbered sections used the chapter, then as soon as you got the chapter locked into place you could start to number them Diagram 3.1, Diagram 3.2, etc.

If this was done, someone would still need to make a second pass (after test typesetting was done), but this would be for the contents at the start of the book. That sort of thing needs to be done anyway (unless your structure allows you to automatically generate a ToC for things that are not chapter headings and sub-headings).

That interior is a world of its own—a world lit by a magical sun.

Hmm. I didn't realise the inner sun was magical, but then I suppose that is because, from a fantasy point of view, an inner sun does not need to be magical to work. What sort of magical properties does it have? Is it the sun that causes the Spell of Preservation to shine down onto the inner surface or something like that?

The Worldshield
Although MYSTARA is smaller than out earth—as well as being hollow—its gravity is the same.

I think you meant "...than our Earth..." here.

This is due to a layer of magical molten rock that runs through the center of MYSTARA’s crust.

Ironically, in Spelljammer, the Worldshield wouldn't need to be magical. I can see PCs trying to mine Worldshieldstone and use it somewhere (maybe by smelting it down to create Worldshieldmetal). I hope there is a rule for this somewhere later on. You have me wondering if Red Steel might somehow be related to this layer.

Called the Worldshield by the Immortals, this layer of lava produces a gravitational field that pulls things toward it from both sides.

Hmm. Does this mean that the people of Mystara don't know about the Worldshield?

Not all of the Worldshield is molten. The lava has hot spots and cool spots, and in some areas it’s solidified. Natural tunnels and caves—and a few artificial passages and mines—can penetrate the Worldshield in these areas. There are even a few spots where the Worldshield remains solid all the way through MYSTARA’s mantle. Tunnels through this solidifies lava can provide access between the HOLLOW WORLD and MYSTARA’s outer surface. Gravity tends to work in strange ways in these areas, though. “Up” and “down” are erratic at best, shifting with the slow movements of the still-molten Worldshield that surrounds the cooler, solid areas.

The introduction of the solid bits of the Worldshield looks a bit awkward for some reason. I'm not sure why, but it felt like you were going back on yourself. I wonder if it would work better with the forth sentence moved before the third sentence, so that you got this:

Not all of the Worldshield is molten. The lava has hot spots and cool spots, and in some areas it’s solidified. There are even a few spots where the Worldshield remains solid all the way through MYSTARA’s mantle. Natural tunnels and caves—and a few artificial passages and mines—can penetrate the Worldshield in these areas. Tunnels through this solidifies lava can provide access between the HOLLOW WORLD and MYSTARA’s outer surface. Gravity tends to work in strange ways in these areas, though. “Up” and “down” are erratic at best, shifting with the slow movements of the still-molten Worldshield that surrounds the cooler, solid areas.

The Worldshield is strongly anti-magical. Mortal magic generally does not work within three hundred miles of the lava layer. (There are fluctuations in this effect, but they tend to be localized and temporary.) This anti-magic effect extends across both polar openings in a band 600 miles thick.

I didn't realise this detail before. I would love to see a diagram that shows the empty zone of air, across one of the polar openings, that is anti-magical.

The Skyshield
In MYSTARA’s Prime Material Plane, most worlds with atmospheres also have Skyshields.

IIRC, 3e has dropped the word "Prime" and things are generally written as if there is only one "Material Plane". I am not saying that "Alternate Material Planes" no longer exist, but it seems as if most campaign settings are written from the point of view that they are the only world that exists.

In any case, I think you are dropping in a second issue (other worlds) that might not need to be dealt with in this section. I think that you could ignore places except Mystara, at this point and then perhaps add an Other Worlds section at the end that says something along the lines of: "Other worlds are known to exist beyond the Skyshield. Out of these worlds, most of the ones with atmospheres have their own Skyshields." A section like this could also touch on everything else (like Hollow Other Worlds or Worldshields*). If you do touch on the various aspects of Other Worlds, then I would suggest you tackle them in the same order as your Mystaran sections.

* = I would personally advocate making Worldshields (and maybe hollow planets) a universal thing for any fanon worlds you add to Mystara, as that would keep "gravity" as a single concept. However, as this is the Mystara Campaign Setting - not a "Mystaraspace" suppliment, I'm not sure how far into this sort of thing you want to go. Forgotten Realms Campaign Setting has one small 3 page section that covers the area beyond Faerun. It might be better for you to concentrate the majority of your book on some sort of core area of the surface.

Occassionally, the Skyshield temporarily develops a rip or tear. This may be caused by the passage of objects (meteors, for example) or by natural but unexplained fluctuations in the Skyshield’s strength. Whenever a tear occurs, atmosphere escapes into the void with incredible force. The stream of air creates a freak tornado, nown as a ripstorm, whirlhole, or Vortigern Vortex (after the Alphatian wizard who first studied the phenomenon).
In clear skies, these vortexes appear as shimmering, dancing funnels which extend up as far as the eye can see. In cloudy skies, they suck the clouds directly beneath the tear into a ferociously whirling spiral up to the edge of the atmosphere. Certain brave adventurers have learned how to ride these ripstorms up and out through the Skyshield.

I can see someone wanting some sort of rules for the Skyshield getting ripped. You have a healing rule, but not one for breaking the Skyshield. Mind you, perhaps this is something for a "Mystaraspace" supplement to tackle in more detail, as most GMs and players will not need this information.

The Atmosphere
Characters above 15,000 feet (on a high mountain, riding a dragon, or whatever) are at a -2 to hit and damage rolls and on all saving throws and skill rolls.

Looks like you are using the sickened condition:

The character takes a -2 penalty on all attack rolls, weapon damage rolls, saving throws, skill checks, and ability checks.

If that is the case, then perhaps you should specifically name this "Altitude Sickness", say that people become sickened. You still could summarise the condition if you want, but specifically naming it could make it easier for a person using Pathfinder rules, for a Mystara game, to check to see that Pathfinder has the same rule.

BTW: The SRD sentence looks a bit nicer than yours (it includes ability checks, which you didn't and attack rolls is better, because in 3e people occasionally use attack rolls when they don't want to hit people). Perhaps it might be good to say something more like:

The Atmosphere
Characters above 15,000 feet (on a high mountain, riding a dragon, or whatever) suffer air sickness. As per the sickened condition they take a -2 penalty to attack and damage rolls and on all saving throws and skill rolls.

Don't forget that there are a bunch of weird characters in 3e rules that use monster races that were previously inaccessible to players. Any sort of creature with a slow metabolism would probably work differently (it might suffer no penalties, less penalties or have a delayed onset) and any sort of creature that does not breath air should suffer no ill effects. The Endurance feat should probably also allow a character to try to delay the onset of symptoms of air sickness (this would require a "Constituition save to avoid..." rule). I think this rule might need to be revised to take that sort of aspect of the 3e rules into account.

If you want to introduce an effect above 15,000 feet, I think that using the fatigued condition might also be appropriate (either as well as altitude sickness or instead of it). Any creatures that can bypass fatigue in thin air should (hopefully) already have those rules written for them. Here is a quote to save you clicking:

A fatigued character can neither run nor charge and takes a -2 penalty to Strength and Dexterity. Doing anything that would normally cause fatigue causes the fatigued character to become exhausted. After 8 hours of complete rest, fatigued characters are no longer fatigued.

I would suggest that "rest" would not apply to high altitude and that a character would need to travel below 15,000 feet and spend 8 hours resting there to get back to normal. I also think that, certain things should escalate the character to the exhausted condition:

An exhausted character moves at half speed and takes a -6 penalty to Strength and Dexterity. After 1 hour of complete rest, an exhausted character becomes fatigued. A fatigued character becomes exhausted by doing something else that would normally cause fatigue.

Again, I think that the character should spend 1 hour resting below 15,000 feet to drop down to fatigued.

If you use all three of these conditions together, then you are going to limit the amount of time a PC can spend that high. As they push themselves to the limit, they will suffer more ill effects.

Above 20,000’ altitude, oxygen-breathing characters and creatures begin to suffocate (see DMG Chapter 8, “Suffocation”). Special breathing gear, magical items, or spells such as create air and survival (created by Alphatian mages for use in their skyships) can help keep characters alive above 20,000 feet.

I've just looked at the SRD and it is a bit of a mess, with rules about this scattered around. Firstly you have two types of suffocation. And secondly, the Endurance feat and even the Swim skill have stuff to say on the subject!

I think it might be worth reviewing these things (perhaps in another thread if you want to avoid clutter) so that Mystara Campaign Setting can sort out the mess and present GMs with a system that takes everything into account.

I personally think that you should be going with the slow suffocation below the Skyshield (as it is the least lethal of the two rules). Above the Skyshield the standard suffocation (the more lethal) would probably be more appropriate as the person has no air with them (and when they breath out they are screwed). My reason for arguing the split like this is that, below the Skyshield the character may be able to attempt to suck a few bits of oxygen from the air, while in vacuum they obviously cannot. The fact that they are in "dead air" rather than "no air" should make some sort of mechanical difference. If you were to make the split this way, then I think the feel of a character going that high, would be more akin to them burning up the remaining oxygen reserves in their lungs and blood.

I think the standard slow suffocation rule will still need a tweak:

Slow Suffocation

A Medium character can breathe easily for 6 hours in a sealed chamber measuring 10 feet on a side. After that time, the character takes 1d6 points of nonlethal damage every 15 minutes. Each additional Medium character or significant fire source (a torch, for example) proportionally reduces the time the air will last. When a character falls unconscious from this nonlethal damage, she drops to -1 hit points and is dying. In the next round, she suffocates.

Small characters consume half as much air as Medium characters. A larger volume of air, of course, lasts for a longer time.

First, they are not in a sealed chamber, so that needs to go. Other characters and things like fire would also not make a difference in open air. And I also think that volume would not make a difference. Perhaps you could cut this down to something a bit more like this:

Above 20,000’ Altitude

Above 20,000’ altitude a character begins to slowly suffocate. The character takes 1d6 points of nonlethal damage every 15 minutes. When a character falls unconscious from this nonlethal damage, she drops to -1 hit points and is dying. In the next round, she suffocates.

There is no atmosphere beyond the Skyshield—either around MYSTARA or within he HOLLOW WORLD. Unprotected characters caught in the airless void are considered to be holding their breath from the time they leave the atmosphere. Even if they can survive the lack of air, characters exposed to the void beyond MYSTARA for more than ten minutes must make a Fortitude save (see DMG Chapter 8, “Cold Dangers”). Within the HOLLOW WORLD, the void is merely pleasantly cool.

According to the SRD, cold dangers are dependent on temperature. So you are going to need to set a temperature for space to make 3e Mystara work**.

** = Arg! All these "gatecrashing" rules are going to have everyone turning to C&C!

From the fact that you have set your saves every ten minutes, I can reverse engineer your post to see that you seem to be suggesting that the temperature of space is between 0 degrees and -19 detrees Fahrenheit. (Once the temperature drops to -20 the damage becomes lethal and the checks rise to once per minute.)

I assume the space between the Hollow World and its sun is above 40 degrees Fahrenheit as you don't suggest a check.

[Gawain_VIII]

Great stuff.

Thanks!

I've got a couple of comments and "nit picks" that you may wish to consider.

EDIT: Wow, this turned out to be a lot of "nit picks", mostly down the SRD being all over the place about a couple of things.

Nit-pick away!

Generally, I am not a fan of TSR's habit of putting their trademarks into ALLCAPS. It seems to be some sort of legal thing, rather than something designed for readability. I would much rather see Mystara, Mystara or even Mystara than MYSTARA.

This is actually small-caps, but when i copy-pasted the text, it didn't translate well. I took the inspiration from WotC, but for a much more pragmatic reason--to differentiate between the world and the setting.

"page X" - With the "page X" thing, someone is going to need to typeset the entire Mystara Campaign Setting, to place everything in the right place before you can work out the pages of all the "page X" placeholders. Then you are going to need to have people go through the thing and hunt down all the "page X"s and replace them with the right pages. I have heard of a few commercial products going to the press with a few placeholders left in them. Margaret Weis Press dropped the ball with at least one of the Dragonlance books.

That is something I'll have to watch out for, but I chose to use this method so I don't assign a number, then later go back and re-number everything after a new table or page, which was not originally planned, is interted.

Hmm. I didn't realise the inner sun was magical, but then I suppose that is because, from a fantasy point of view, an inner sun does not need to be magical to work. What sort of magical properties does it have? Is it the sun that causes the Spell of Preservation to shine down onto the inner surface or something like that?

It's actually a permanant gate to the Elemental Plane of Fire, which Ixion opened when he started helping Ka develop her discovery. I left the description as "magical" for spoiler purposes. It's been a while since I looked at it, but, IIRC, the true nature is detailed elsewhere.

I think you meant "...than our Earth..." here.

You are correct.

Ironically, in Spelljammer, the Worldshield wouldn't need to be magical. I can see PCs trying to mine Worldshieldstone and use it somewhere (maybe by smelting it down to create Worldshieldmetal). I hope there is a rule for this somewhere later on. You have me wondering if Red Steel might somehow be related to this layer.

This is a function of Mentzerian physics being more closely related to real-world physics than Grubbian physics. No, the world shield doesn't have anything to do with red steel (in canon).

Hmm. Does this mean that the people of Mystara don't know about the Worldshield?

Typically speaking, yes. Although some high-level wizards and scholars might guess at it's existance, this should be the rare exception to the rule.

The introduction of the solid bits of the Worldshield looks a bit awkward for some reason. I'm not sure why, but it felt like you were going back on yourself. I wonder if it would work better with the forth sentence moved before the third sentence,

Agreed.

I didn't realise this detail before. I would love to see a diagram that shows the empty zone of air, across one of the polar openings, that is anti-magical.

There is a diagram available. I'll see if I can't find one to post. This is also why a spelljammer would crash if it tried to fly through one of the poles--forcing it's crew (if they survived) to be land-bound (what a horrible fate!).

IIRC, 3e has dropped the word "Prime" and things are generally written as if there is only one "Material Plane". I am not saying that "Alternate Material Planes" no longer exist, but it seems as if most campaign settings are written from the point of view that they are the only world that exists.

In any case, I think you are dropping in a second issue (other worlds) that might not need to be dealt with in this section. I think that you could ignore places except Mystara, at this point and then perhaps add an Other Worlds section at the end that says something along the lines of: "Other worlds are known to exist beyond the Skyshield. Out of these worlds, most of the ones with atmospheres have their own Skyshields." A section like this could also touch on everything else (like Hollow Other Worlds or Worldshields*). If you do touch on the various aspects of Other Worlds, then I would suggest you tackle them in the same order as your Mystaran sections.

While this is true, due to the dimensional nature of Mystara's Multiverse cosmology, there are in fact multiple Material Planes (in different dimensions), so the distinction needs to be made.
While most single-planet settings assume a single-world POV, in the Multiverse, multiple planets are KNOWN to exist. (The fact that some of them contain intelligent life, and especially magic-wielding life, is unknown, however.)

* = I would personally advocate making Worldshields (and maybe hollow planets) a universal thing for any fanon worlds you add to Mystara, as that would keep "gravity" as a single concept. However, as this is the Mystara Campaign Setting - not a "Mystaraspace" suppliment, I'm not sure how far into this sort of thing you want to go. Forgotten Realms Campaign Setting has one small 3 page section that covers the area beyond Faerun. It might be better for you to concentrate the majority of your book on some sort of core area of the surface.

I'm undecided on this part, personally, but it's well beyond the scope of the book.

I can see someone wanting some sort of rules for the Skyshield getting ripped. You have a healing rule, but not one for breaking the Skyshield. Mind you, perhaps this is something for a "Mystaraspace" supplement to tackle in more detail, as most GMs and players will not need this information.

I'm a firm advocate of rules-light. Unfortunately because of the nature of 3e, I'm not able to be as light as I'd like... but for the sake of this question, the rule is "it rips when and how the DM says it rips".

Looks like you are using the sickened condition:

Thank you. I was unaware of this condition. Altitude sickness it is!

BTW: The SRD sentence looks a bit nicer than yours (it includes ability checks, which you didn't and attack rolls is better, because in 3e people occasionally use attack rolls when they don't want to hit people). Perhaps it might be good to say something more like:

The phrase "to hit" was left over from the original source, which used RC rules.

Don't forget that there are a bunch of weird characters in 3e rules that use monster races that were previously inaccessible to players. Any sort of creature with a slow metabolism would probably work differently (it might suffer no penalties, less penalties or have a delayed onset) and any sort of creature that does not breath air should suffer no ill effects. The Endurance feat should probably also allow a character to try to delay the onset of symptoms of air sickness (this would require a "Constituition save to avoid..." rule). I think this rule might need to be revised to take that sort of aspect of the 3e rules into account.

These effects are specific to those creatures. As the DMG points out, "specific beats general". So the "specific" rules of those monsters would override the "general" rule presented here, when applicable.

If you want to introduce an effect above 15,000 feet, I think that using the fatigued condition might also be appropriate (either as well as altitude sickness or instead of it). Any creatures that can bypass fatigue in thin air should (hopefully) already have those rules written for them.

Good suggestion. I'll consider it...

I would suggest that "rest" would not apply to high altitude and that a character would need to travel below 15,000 feet and spend 8 hours resting there to get back to normal. I also think that, certain things should escalate the character to the exhausted condition

Agreed.

Again, I think that the character should spend 1 hour resting below 15,000 feet to drop down to fatigued.

If you use all three of these conditions together, then you are going to limit the amount of time a PC can spend that high. As they push themselves to the limit, they will suffer more ill effects.

Comment superfolous.

I've just looked at the SRD and it is a bit of a mess, with rules about this scattered around. Firstly you have two types of suffocation. And secondly, the Endurance feat and even the Swim skill have stuff to say on the subject!

Again, specific beats general. The "original" reference should suffice for most cases... where it doesn't, it'll be up to the DM to determine if a specific rule applies or not.

I think it might be worth reviewing these things (perhaps in another thread if you want to avoid clutter) so that Mystara Campaign Setting can sort out the mess and present GMs with a system that takes everything into account.

I deliberately didn't offer every possible scenario for two reasons. 1: This is a setting book, not a rulebook. 2: The rules for various scenarios can be located elsewhere--there's no need to duplicate what already exists.

According to the SRD, cold dangers are dependent on temperature. So you are going to need to set a temperature for space to make 3e Mystara work**.

** = Arg! All these "gatecrashing" rules are going to have everyone turning to C&C!

From the fact that you have set your saves every ten minutes, I can reverse engineer your post to see that you seem to be suggesting that the temperature of space is between 0 degrees and -19 detrees Fahrenheit. (Once the temperature drops to -20 the damage becomes lethal and the checks rise to once per minute.)

I assume the space between the Hollow World and its sun is above 40 degrees Fahrenheit as you don't suggest a check.

Fair assumption. I wasn't aware that the cold rules were temperature specific. When I researched the cross-reference, I probably saw the topic in the index and didn't read what it said. Regardless, with the duration of the checks already defined, I don't see a need to place a specific temperature--as long as whatever the DM determines the temperature is falls within the range for the rule presented here.

Did I miss anything? PLEASE!!!! More feedback! Even better--submit something yourselves. Even Bruce and Aaron had a staff working with them. This project has taken nearly 5 years because I'm doing it all by myself.

Cheers,
Roger

[Gawain_VIII]

Updated with BigMac's suggested edits and new OW dimensions previously agreeed upon in this poll.

[ripvanwormer]

If the World-Shield is magical, what happens to it during the Week Without Magic, a time when even Immortal-created effects like the Hollow World's sun went dark? Is everything on the planet thrown into the sky as gravity fails? Clearly not. Granted, the Hollow World boxed set does specifically refer to the World-Shield as "a belt of magical matter several miles thick," but this is not "magic" in any form that effects that target magic can affect. Even Immortal divinations cannot penetrate it. I think it's essentially not "magic" in game terms, although it remains "magical" in the sense of something wondrous and unexplainable. The word "extraordinary" might be better, to make it clear that the World-Shield doesn't function as magic as far as the rules of the game go.

While the fantasy physics that Bruce Heard invented in Dragon #160 are definitely different from the ones Jeff Grubb invented for Spelljammer, they aren't more like the real world's physics than Grubb's physics is. I'd say they're equally fantastic. Note that the presence of skyshields would make Bruce Heard's notes on the need for rings of mountains or concave surfaces to hold air in irrelevant. Odd, since I think both skyshields and Heardian physics were introduced in Dragon #160. That makes me think that Bruce Heard intended the skyshield to be something unique to Mystara, not necessarily found on all worlds, although it'd be more useful in building campaigns if skyshields were around every flatworld or shardworld (since it'd allow for more geographical flexibility).

But maybe I'm wrong, because Dragon #160's Princess Ark episode mentions the skyshield, but never really defines it. Where are skyshields originally defined?

One advantage of Heardian physics, however, is that there's really no reason that it couldn't be a standard property of a hollow sphere that gravity points toward the ground on both the inside and the outside. While he didn't mention this in his article, it's no more irrational than the odd gravities he assigns to other geometric states (for example, coneworlds and discworlds). Postulating magical lava or whatever isn't required. In that sense, there's something of a disconnect between Bruce Heard's article and the Hollow World boxed set. I wonder if the only reason he didn't mention hollow worlds in Dragon #160 is that the Hollow World hadn't been introduced yet (it was formally introduced in the next issue), and he wanted to keep it a surprise.

The Hollow World boxed set defined the Hollow World's sun as "a small, permanent Gate to the Sphere of Energy." I always assumed this was an Outer Plane, rather than the Elemental Plane of Fire.

In the D&D cosmology created by Frank Mentzer, the plane that the D&D world exists in is known simply as the Prime. In 3rd edition, this plane is known as the Material Plane. The term "Prime Material Plane" only appears in AD&D. For the sake of a 3rd edition conversion, it should probably be referred to as the Material Plane.

[Giorgio]

The Skyshield
In the Prime Material Plane where Mystara is located, most worlds with atmospheres also have Skyshields.

I agree with the others post above that the correct term should be "material plane".

After reading the rules on the Skyshield I was wondering if you should have it in a separate section. Have this section just be the "fluff" description for the GM to understand what the Skyshield is and how it works, and a separate easy to reference section with the "crunch" that explains what rules come into play.

I don't think the Skyshield is a plot element that needs rules in its description as I don't see many GMs needing this information on a regular basis.

[Gawain_VIII]

The Skyshield
In the Prime Material Plane where Mystara is located, most worlds with atmospheres also have Skyshields.

I agree with the others post above that the correct term should be "material plane".

After double-checking Rip's references, I'm more inclined to agree, now.

After reading the rules on the Skyshield I was wondering if you should have it in a separate section. Have this section just be the "fluff" description for the GM to understand what the Skyshield is and how it works, and a separate easy to reference section with the "crunch" that explains what rules come into play.

I don't think the Skyshield is a plot element that needs rules in its description as I don't see many GMs needing this information on a regular basis.

The skyshield is not a significant plot element, and does not justify being mentioned more than once. However, since this is the only place it is going to be mentioned, it's only fitting that both fluff and crunch are identified.