In an area known as The Pits lays waste to a lower level, commonly referred to as "The Depths" in which a player is submerged into hell after passing Golem monsters.
In the magma-filled caves underneath the depths of The Pits, 2 common magma monsters resides, being the magma bat and the magma knight, as well as two types of wizards who will teleport you up. The wizard changes depending on day/night cycle.
Loot and Bosses
The Pit Depth mobs (except the boss itself) drops magma brain chunks while the Magma Knight as a minor chance to drop the Inferno Sword, which sells for 32,000 gold, or useable with its base damage of 72.
The current end-game boss, The Magma Brain, spawns in the magma-filled caves underneath the depths, close to one of the entrances to this cave system.