Are there other options that fit better with the theme, are more unique, and enhance gameplay?
What about "the LURE," a bone-shaped ONE-USE die:
If, after the monster dice are rolled, you've realized the monster you're fighting is too powerful, throw the LURE die. If it comes up with the bone-shape on the face, have the monster attack the player to your right.
And maybe if the monster is not defeated, you can sneak in and steal the treasure while it is wounding the other player?