Accretion Disc

Infalling material around a collapsed object, heated by friction until it outshines a star. Matter in the disc moves inward, as does any vessel that stops using thrust. Time runs slow near the object, and a creature outside a hull takes tidal damage at the innermost band.

Extraplanetary

Exposure

Vacuum

No pressure and no air to breathe, with survival measured in rounds.
- Countdown
  
  Without a seal, a creature holds out for a number of rounds equal to its Constitution modifier, minimum 1. At the end of that time its hit points drop to -1, unless they are already lower, and it is dying. It cannot be stabilized or regain hit points until it can breathe.
- Decompressed
  
  Exposure inflicts the Decompressed condition, which a return to pressure does not by itself remove.
- Holding your breath
  
  Holding a breath in vacuum ruptures the lungs. A creature that does so takes 2d6 damage on the first round and gains no benefit from the attempt.
- Sound
  
  Sound does not travel. Verbal spell components, shouted orders and Perception by hearing all fail across open vacuum. Suit comms and touch are the only channels.
- Unfiltered light
  
  Without air to filter it, the star's output arrives unreduced. An hour of unshielded exposure in direct sunlight counts as a failed Contaminated Atmosphere save against radiological dose.
Extreme Heat

Temperatures above about 100 degrees Fahrenheit in shade, or anywhere near a working vent.

CON save, DC 10, rising by 1 for each hour after the first. End of each hour. One level of exhaustion.
- Sealed and armored
  
  A creature in medium or heavy armor, or in a sealed suit without active cooling, has disadvantage on the save.
- Water
  
  A creature with its full water ration has advantage on the save. One without any fails automatically.
- Cooled
  
  Active cooling, a Rift effect naming heat, or Resistance to fire damage removes the save.
High Gravity

Gravity above about 1.5g, where objects and creatures weigh more and falling damage is doubled.

CON save, DC 12. End of each hour of exertion. One level of exhaustion.
- Weight
  
  Carrying capacity is halved, and a creature's speed is reduced by 10 feet.
- Falls
  
  Falling damage is doubled, and a fall of 10 feet or more knocks a creature Prone with no save.
- Ranged weapons
  
  The long range of any thrown or ballistic weapon is halved.
- Adapted
  
  A creature native to a high-gravity world, or one with a feature naming gravity, ignores all of the above.
Zero Gravity

Free fall, where there is no down, no moving body stops on its own, and a missed handhold leaves a creature adrift.
- Movement
  
  Moving requires a surface to push from. A creature with nothing in reach continues in the direction it last moved until it reaches something.
- Changing course
  
  Changing direction mid-drift requires a DC 12 Dexterity (Acrobatics) check. On a failure the creature continues as it was.
- Melee
  
  An unanchored melee attack has disadvantage and pushes the attacker 10 feet away from the target after it resolves.
- No falling
  
  There is no up, no down and no falling damage. A creature cannot be knocked Prone, and the Prone condition does not apply.
- Mag boots
  
  Magnetic boots or a tether remove every entry above while a ferrous surface is underfoot, at the cost of half movement.
Rift Flux

Ambient Rift Energy at a high, unstable density, where channeling is stronger and less reliable.

WIS save, DC 13. End of each hour. Your next spell attack roll has disadvantage, or the target of your next spell that forces a saving throw has advantage on it. Roll once on the Surge Table.
- Dense field
  
  A spell cast here that deals damage or restores hit points adds its level to one of its damage or healing rolls, and a cantrip adds 1. A spell that does neither gains nothing. The bonus cannot be declined.
- Unstable
  
  A natural 1 or 2 on a spell attack roll, a target's natural 19 or 20 on a saving throw against a spell, and any failed concentration save each roll on the Surge Table in the GM's Manual.
- Instruments
  
  Anything calibrated against a stable Rift background reads wrong. Navigation, dating and detection checks that rely on one have disadvantage.
- Warded
  
  A ward, a null field or a feature naming Rift density removes the save and the Surge rolls. The damage and healing bonus goes with them.

In play

Inward

Every round spent in the disc without thrust moves the vessel one band closer to the object. There is no drifting outward.
Tidal

High Gravity applies and worsens with each band. At the innermost band, a creature outside a hull takes 4d10 bludgeoning damage per round.
Time

Close to the object, time runs slow relative to outside. A stay measured in hours costs days or years elsewhere, at the GM's rate.
Ionizing dose

Unshielded, a creature gains a level of exhaustion each hour. A long rest does not clear it. A Medicine check at DC 12, a restorative spell or antiradiation drugs remove it. Rated shielding removes the effect, and most powered plate raises the interval to four hours.