Chamber of Fire, a.k.a. Goblin Go BOOM!
You enter a massive underground chamber that appears to be some sort of temple. At the far end is the goblin leader performing some sort of ritual to a large idol of Bane. In between you and the altar are two narrow bridges of stone that hang over a deep chasm of flowing lava. The goblin leader turns to face you and begins shouting, motioning several goblins in front of him to attack.
Download the full encounter here: Chamber of Fire, a.k.a. Goblin Go BOOM!