Mt. Erebus

That seems to be all of them... Still! Something is moving there, or is it lava glow?

After killing the lava elemental:

Tough son of a bitch... now to get that shiny object he left behind...

Better leave, before this thing blows!

If the Lava elemental spawned and the player did not kill it:

There goes my beard... at least I'm still alive.

If all enemies and the Lava elemental is dead:

Lava elementals my ass. I don't care.

Pulling the levers will cause the center walls to go down, one by one. Regardless of the order the levers are pulled, the walls fall from outermost to innermost.

Flying enemies have their starting position randomized on lava tiles, while landlocked enemies are static. Killing all enemies will spawn a Lava elemental, killing which drops a Lava element. The random items are armors and boots that can normally drop on level 25. These armors and boots are five times as likely to be an Exotic or Unique, and there's additionally a three times increased chance that the Lava Armor will be one of them if the player hasn't found it prior.

Note that if using a Phase device or Hell Staff, it is possible to teleport inside the "mountain" before raising it, where the player will then be softlocked if they have no means to teleport back out, so it's advised to avoid using those items to get across the lava without at least also packing a Homing phase device in case you do get stuck.