MC lived a life like the perfect saintess. Her teacher lied to her that saintess can only heal, was betrayed by the prince and warrior and killed by the people by putting her in a cross and burning her, she then cursed for revenge.
Then a fairy saying that saintess and warriors will be immediately resurrected when they were killed but it wasn't thought to her. He said that saintess can control all elements and magic, so MC exacted her revenge by killing a person involved in killing her sister. Turning the fucker to a zombie and starting a zombie apocalypse.
So That's How, The Saintess Became The Devil Of Revenge