Vorpal

Originally created as a means of slaying the legendary jabberwock, vorpal weapons prove equally effective against nearly any foe with a head.

Activate—Snicker-Snack [R] (concentrate, death, incapacitation)

Trigger You roll a natural 20 on a Strike with the weapon against a creature that has a head, critically succeed, and deal slashing damage.

Effect The target must succeed at a DC 37 Fortitude save or be decapitated. This kills any creature except ones that don't require a head to live. For creatures with multiple heads, this usually kills the creature only if you sever its last head.