Underground Necro

The UnderGround Necro forms when the Necro spreads to the cavern layer and below. It is composed of Skelestone and Skelesand, Floating Skulls, and Necro Alters.

Appearance
It's background features white stone with many skulls, bones, and rarely a very large skull. There is a 3.33 chance of skelestone in a small area to be replaced with a Necro alter, which resembles a Jungle shrine, but with skelestone brick, a blue torch, and an unlocked shadow chest. Floating skulls appear as well, the destruction of three of them summons the Eater of Suns.

Demon alters remain the same, but shadow orbs disappear, stopping the Eater of Worlds from spawning without Worm Food.

The Underground Necro becomes much calmer after the defeat of Skullet, and replaces many regular underground necro monsters with less skeletal counterparts.

Enemies
(The following monsters spawn whenever Skullet is defeated, if something is listen above is not listed below, it doesn't spawn after Skullet's defeat)
 * Destroyer of Souls
 * Swallower
 * Servant of Skeletron (much more common than above ground)
 * Rattler
 * Necro Ripper
 * Spiked Skeleslime
 * Dark caster
 * Light Caster
 * Skullet