The Underworld

Deep under the Cavern Layer, The Underworld begins. The spawning of Fire Imps and Bone Serpents and a change in background texture marks the beginning of The Underworld. It is made of ash blocks, lava, and Hellstone ore. There are also Hellstone Brick buildings scattered across the landscape, which sometimes contain Hellforges.

The Underworld is the most challenging environment so far, giving you access to Hellstone, which can be smelted in a Hellforge to create some of the the strongest armors, weapons and tools. A nice tip is to find a large pond of water in a cave above, and dig down until the water flows down into The Underworld. If you have enough water, you can easily collect Obsidian without worrying about falling into lava.

Monsters in The Underworld

 * Fire Imp
 * Bone Serpent