SCP 323 The Wendigo Skull

Equipped creature has base power and toughness
5/6, gains double strike, loses all other abilities,
and must attack each combat if able.
Whenever a creature damaged by equipped
creature dies, or a player sacrifices a creature, put
a +1/+1 counter on equipped creature.
At the end of each end step, if no +1/+1 were put
on equipped creature, put a -1/-1 counter on it.
Equip - sacrifice a creature
Whenever SCP 323 becomes unattached from a
permanent, sacrifice that permanent.