Underworld Domain

The Underworld Domain is a structure added by the Split Mod that spawns upon world generation and lies just above Underworld. The biome features its own unique tiles, backdrops, enemies, loot and music. The biome is mostly composed of Basaltite and Basaltite Brick, and chains together. The biome can't be mined without a Cobalt pickaxe (or any pickaxe of 110% power and higher), preventing early game exploration, and if one were to enter the biome, Basalt geysers form around the player, dealing massive damage and killing the player if they come into contact with the geyser.

Once the world enters hardmode after the Wall of Flesh has been defeated, Chthonic Pearls now start forming around the basaltite, making it a good indicator when looking for the biome.

Fishing
Fishing in the lets you obtain biome-related items:
 * can be caught with any fishing power and only in lava
 * , needs to be unlocked with Tectonic Key, similarly to a Tectonic Chest

Tips

 * The biome is very dangerous at the start of hardmode due to the basalt geysers, one way to counter this is by wearing the full set of Tectonic armor as the bonus set prevents geysers from forming when entering the biome.
 * Breaking any Monster cages should also be avoided as they can spawn any dangerous hardmode enemies that will kill any unprepared player.

Trivia

 * The music heard in the is Basalt. Composed by the artist, Instrex.