Have Moris work off of a token system.

Ebony Memento Mori: Every time you hook a survivor, gain one token. You may spend 3 tokens to kill a survivor who has already been hooked by your own hand.


Ivory Memento Mori: Every time you hook a survivor, gain one token. You may spend 5 tokens to kill a survivor who has already been hooked by your own hand.


This would make Moris into something the killer has to work for, instead of an instant win state. It would prevent tunneling while retaining the fear of being killed instantly.