Lava

Lava is a tile found in Dungeon Keeper and Dungeon Keeper 2. Creatures will not walk on this tile without taking damage and Imps cannot claim it, so it has to be traversed using a Bridge. 
==Dungeon Keeper==
In Dungeon Keeper, most creatures cannot walk on lava without being harmed, so will avoid it. Creatures can walk over lava, but will take constant damage. When a Dragon sleeps next to lava, it gains experience. Creatures can be moved onto lava by being blown (Wind spell) or blasted (e.g. Word of Power or Time Bomb spell) onto it, or by player means (selling the Bridge under them or using Possess Creature to force them to walk across it).
The creatures who can traverse lava unharmed in Dungeon Keeper are:
* (immune to lava)
* (immune to lava)
* (immune to lava)
* (immune to lava)
* (airborne creature)
* (airborne creature)
* (airborne creature)
* (can use the Flight spell)
* (can use the Flight spell)
Lava Traps will, when triggered, permanently turn the tile it is on into a lava tile.
Creatures will not teleport across lava if they cannot otherwise negotiate it without taking damage from it.
The manual falsely states that Cave-In can be used to cross lava; however, it's likely that this was true (or at least planned) at one point.
==Dungeon Keeper 2==
Lava differs slightly in Dungeon Keeper 2 in that you cannot use Possession to make a creature walk across it unless they can themselves walk across it without taking damage, although you can make them by selling (or burning, in the case of the Wooden Bridge) the bridge under their feet. If this is done while under Possession, the entire screen turns completely red due to the damage being taken, making it quite hard to use as a means to get around. Other than that, lava is exactly the same.
The creatures who can traverse Lava unharmed in Dungeon Keeper 2 are:
* (immune to lava)
* (immune to lava)
* (immune to lava)
* (airborne creature)
* (airborne creature)
* (can turn into a bat, allowing it to fly over lava)