Teval's Judgment

Whenever one or more cards leave your graveyard, choose one that hasn't been chosen this turn —
• Draw a card.
• Create a Treasure token.
• Create a 2/2 black Zombie Druid creature token.

Timeless Witness

When this creature enters, return target card from your graveyard to your hand.
Eternalize {5}{G}{G} ({5}{G}{G}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Human Shaman with no mana cost. Eternalize only as a sorcery.)

Colossal Grave-Reaver

Flying
Whenever this creature enters or attacks, mill three cards.
Whenever one or more creature cards are put into your graveyard from your library, put one of them onto the battlefield.

Teval, the Balanced Scale

Flying
Whenever Teval attacks, mill three cards. Then you may return a land card from your graveyard to the battlefield tapped.
Whenever one or more cards leave your graveyard, create a 2/2 black Zombie Druid creature token.

Will of the Sultai

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Target player mills three cards. Return all land cards from your graveyard to the battlefield tapped.
• Put X +1/+1 counters on target creature, where X is the number of lands you control. It gains trample until end of turn.

Death Baron

Skeletons you control and other Zombies you control get +1/+1 and have deathtouch. (Any amount of damage they deal to a creature is enough to destroy it.)

Kotis, Sibsig Champion

Once during each of your turns, you may cast a creature spell from your graveyard by exiling three other cards from your graveyard in addition to paying its other costs.
Whenever one or more creatures you control enter, if one or more of them entered from a graveyard or was cast from a graveyard, put two +1/+1 counters on Kotis.

Sidisi, Brood Tyrant

Whenever Sidisi enters or attacks, mill three cards.
Whenever one or more creature cards are put into your graveyard from your library, create a 2/2 black Zombie creature token.