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Gaseous Waters

Primordial gasses can squeeze up from the bedrock under all kinds of bodies of water, bubbling up to explode in coughs of the planet’s birth that can knock creatures out or even kill outright. Every 1d20 minutes while traversing Gaseous Waters, a gas bubble rises up and breaks the surface of the water from a point within 15 feet. Creatures within 30 feet of a gas bubble make a Constitution saving throw or suffer from its effects (as per Table: Gaseous Waters).

Table: Gaseous Waters
d6 Gas DC Effect
1 Corrosive 17 4d4 acid damage
2 Fatigue 15 One level of exhaustion
3 Incapacitating 13 Become incapacitated for 1d4 rounds
4 Incendiary 16 4d4 fire damage
5 Poisonous 14 4d4 poison damage and poisoned until this damage is healed
6 Sleeping 12 Fall unconscious for 10 minutes, until the sleeper takes damage, or someone uses an action to shake or slap the sleeper awake