Mutagenic fog

Version 0.15: This article may not be up to date for the latest stable release of Crawl.

Mutagenic fog is a dangerous kind of cloud, a condensed form of magical contamination. Ending a turn standing within a mutagenic fog cloud will give your character a large dose of contamination, quickly reaching dangerous levels if you spend significant amounts of time in one. Monsters will polymorph instead, occasionally becoming a higher HD creature than they were before.

Mutagenic fog is thankfully very rare, usually found in vaults in the Abyss and Cigotuvi's Fleshworks or emitted if you worship Xom and he thinks this place needs a bit more athmosphere.

History

Prior to 0.15, mutagenic fog inflicted bad mutations on the player each turn, rather than giving them magical contamination.

Mutagenic fog was added in 0.8.