Cthulhu Mythos

Cthulhu Mythos is an event that brings 15 bosses into your world and is started by H. P.'s Book. The bosses are spawned separately with special items. Each boss is part of 1 of 4 elements which are Air, Earth, Fire, and Water. All bosses names were not created by me, but by H. P. Lovecraft /Derleth. Also a few monsters also will start appearing around your world which are the Shaggoth, Shambler,. After beating all Bosses combining all their drops will make the Abominable Slime, which will spawn Abhoth, and killing Abhoth will drop another boss summoning item until all the deity's (49 of them) are defeated.

Fire Bosses

 * Aphoom-Zhah
 * Cthugha

Water Bosses

 * Dagon
 * Ghatanothoa
 * Mother Hydra
 * Zoth-Ommog

Earth Bosses

 * Cyäegha
 * Nyogtha
 * Shub-Niggurath
 * Tsathoggua

Air Bosses

 * Hastur
 * Ithaqua
 * Nyarlathotep
 * Zhar and Lloigor

Disclaimer
I will not add Cthulhu/a Final boss/a New Mode because everyone will be mad.