Karsus's avatar

Karsus' Avatar is a very powerful spell which alters the very disposition of reality. It is even capable of allowing its user to become a god of their choosing, replacing a current god with themselves the moment the spell was completed.

History
The spells origin is unknown, yet dates back to Netheril. Karsus' original notes regarding its creation were never found. Whether the gods were able to defend against the spell, or were aware of its casting, are unknown. Karsus spent well over a decade researching this spell. It is believed Mystra, the reincarnated form of Mystryl, snatched the spell information from the ruins of Karsus' enclave and sent it on an eternal journey to the ends of the universe.

Spell Components
It was so complex that he had to put a stone-filled gizzard of a gold dragon into a mixture of tarrasque blood and 12-headed hydra bile to just enchant one of the material components of the spell. It had a casting time of six hours.