Lava
Lava is a dungeon feature found in places such as the Valkyrie and Monk Quests and the Plane of Fire.
Stepping into lava is dangerous. There is a high risk of getting stuck and dying. If you find yourself stuck in lava, you can jump out, freeze the lava with a cold attack such as by a wand of cold and then dig yourself out with a digging implement like a pick-axe, or pray.
To cross lava, use levitation, fireproof water walking boots, or a cold attack to freeze it. Walking (but not levitating) over lava without fire resistance will damage you every turn you do it.