User can whisper satanic spells

Pros:
-user can remember spells easily
-user can control others
-user can make wounds worse
-user can weaken others

Cons:
-user can only whisper spells, not talk or sing normally
-user can't high in pitch
-user may kill someone or send them to hell
-user can't remember spells with a head injury
-user must must finish spells properly or they will be punished

Weakness: over eating
User's voice will fade and lose what powers there is