Help for the Environment rules for a Black Hole 3.5E/PF1

[Upper_Krust]

There could be:

Terrestrial Hazards: Volcano High temperatures, Arctic Freezing Temperatures, Sea Trench Pressures, Lightning Storms
Gods+: Immune, Godlings: Resistant

Stellar Hazards: Surface of the Sun, Outer Space, Extreme Pressure Environments (Planetary/Stellar cores), Heavy Gravity, Cosmic Storms
Sidereals+: Immune, Gods: Resistant

Dimensional Hazards: Black Holes, Worm Holes, Quasars, Gamma Rays, Time Storms
Demiurge+: Immune, Sidereals: Resistant (a black hole might be used to imprison a sidereal with the high EMF essentially functioning as dead-magic zones).

Universal Hazards: Big Bang (planck) effects, Tears in Reality, Cosmic Cysts, Star Plagues, Collapsing Space
Time Lords+: Immune, Demiurge: Resistant

Multiversal Hazards: Probability Crack, Logic Paradox, Anti-Maxim
Supernals: Immune, Time Lords: Resistant

Just to update, gods in the new 5E book are not auto-immune to natural or cosmic phenomena this ruling is no longer needed because of Damage Threshold (base level = Hit Dice x0.3) which can negate or mitigate effects - especially when coupled with Resistances and Immunities.

For example: An immortal* in Space takes: 18 cold damage, 12 radiant damage and 6 necrotic damage at the beginning of each turn. A Hero-deity (Divine Rank 1) has 30 Hit Dice and a base Damage Threshold of 9. Therefore they would only take the cold and radiant damage each turn spent in Space, their Damage Threshold of 9 negating the Necrotic damage of 6.

*Gods don't worry about breathing.

A Demigod (60 Hit Dice and base 18 Damage Threshold) would take zero damage in space unless they were Vulnerable to Cold or Radiant damage - A God with the Fire Purview would be Vulnerable to Cold damage for instance.

So this way you can still have Gods fighting in Space or any of the other potentially Hazardous environments - Core of a Planet, Gas Giant Storm, Event Horizon etc. These all have a set amount of damage and different damage types - sometimes along with a Condition.

So the Dungeon Master will know battles on the Edge of an Event Horizon are likely deadly to immortals of 'x' Divine Rank, meaningful to immortals of 'y' Divine Rank and ignored by immortals of 'z' Divine Rank. This way they can work within that sweet spot of the 'Meaningful' hazards.

In addition to any Base damage dealt from Hazardous locations there might also be a chance of anomalous 'spatial/weather' occurrences that affect the battlefield. So while fighting in Space you might get caught in a Meteor Shower etc.