Y'ggrosh, the Necrocosm

Lifelink

Undergrowth — When Y'ggrosh, the Necrocosm enters,
put a +1/+1 counter on it for each creature card in your graveyard.

Whenever Y'ggrosh, the Necrocosm attacks, each player mills X cards, where X is equal to the number of +1/+1 counters on it. Then, you may return target creature card from a graveyard to the battlefield under your control with
a Finality counter on it. If you do, you lose life equal to it's mana value.