Flayer of the Hatebound

Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)
Whenever Flayer of the Hatebound or another creature enters from your graveyard, that creature deals damage equal to its power to any target.

Doomed Necromancer

{B}, {T}, Sacrifice Doomed Necromancer: Return target creature card from your graveyard to the battlefield.

Phyrexian Delver

When Phyrexian Delver enters, return target creature card from your graveyard to the battlefield. You lose life equal to that card's mana value.

Coram, the Undertaker

Coram, the Undertaker gets +X/+0, where X is the greatest power among creature cards in all graveyards.
Whenever Coram attacks, each player mills a card.
During each of your turns, you may play a land and cast a spell from among cards in graveyards that were put there from libraries this turn.