Lava

Version 0.11: This article may not be up to date for the latest stable release of Crawl.

An intensely hot pool of molten rock, emitting clouds of sulphurous smoke.

Lava is a type of terrain found in the Dungeon (usually on deeper floors) and many of its branches. It is impossible to cross for most player species, unless you can use Flight or Levitation. Attempting to move onto lava is not allowed normally, but it is possible to accidentally step into lava (and instantly die) if you are confused and try to move while next to lava. The game will prompt you with a Y/N before allowing you to do this.

Having one's means of flight or levitation expire while over lava usually means instant death, unless you can scramble free from it.