Shinigami Mask

{t}: Add one mana of any color. You lose 2 life.
{5}, {ut}: Until end of turn, Shinigami Mask
becomes an X/X Demon creature with menace
where X is equal to the amount of life you've
lost this turn. It's still an artifact.

Powerful life-force and unique chakra affinity are
required to act as a physical conduit for summoning
the powerful death entity.