Psychosis Skulk

(Nonexistent mana costs can't be paid.)
Psychosis Skulk is black.
If you would discard Psychosis Skulk, instead exile it and put it onto the battlefield tapped.
Madness is not a living thing or entity that one can slay, it becomes a part of you, feasting on happiness and joy. It makes the mind decay and lets all trace of bliss rot.