Life Eater Haze
Hazard
Level 22 Obstacle
XP 4150

With a violent hiss, billows of blue-tinged purple gas fill the room. Each gasp of the vile stuff drains your strength and saps your life essence.

Hazard: This strange gas steals the life from those within it.Perception     It takes no check to see the gas.Arcana     DC 24: The character recognizes the life-draining traits of the haze.TriggerWhen a living creature starts its turn in the gas, the gas makes the following attack.Attack * Necrotic, PoisonOpportunity Action      Area the entire room
Target: Each living creature that starts its turn in the gasAttack: +23 vs. FortitudeHit: 1d10 + 6 poison damage, and ongoing 10 necrotic damage (save ends). First Failed Saving Throw: The ongoing damage increases to 15 necrotic. Second Failed Saving Throw: The target loses a healing surge.Countermeasures     Making a close or an area attack that has the radiant keyword nullifies the haze in the affected squares until the end of the attacker’s next turn (or, in the case of a zone, until the zone ends). Those who start their turns in nullified areas are not attacked.

Published in Dungeon Master's Guide 2, page(s) 73.