Auru, Sun Of The Abyss

Eminence — As long as Auru is in the command zone
or on the battlefield, whenever you cast a spell with
mana value equal to or greater than half your life total,
rounded down, you get an omen counter.
Lifelink
When Auru enters, remove all omen counters from
yourself. Then, for each omen counter removed this
way, Auru deals 4 damage to each opponent,
planeswalker and other tapped creature.