Liliana, Untouched by Death

+1: Mill three cards. If at least one Zombie card is milled this way, each opponent loses 2 life and you gain 2 life.
−2: Target creature gets -X/-X until end of turn, where X is the number of Zombies you control.
−3: You may cast Zombie spells from your graveyard this turn.

Champion of the Perished

Whenever another Zombie you control enters, put a +1/+1 counter on Champion of the Perished.

Warren Soultrader

Pay 1 life, Sacrifice another creature: Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Corpse Knight

Whenever another creature you control enters, each opponent loses 1 life.

Archghoul of Thraben

Whenever Archghoul of Thraben or another Zombie you control dies, look at the top card of your library. If it's a Zombie card, you may reveal it and put it into your hand. If you don't put the card into your hand, you may put it into your graveyard.

Diregraf Colossus

Diregraf Colossus enters with a +1/+1 counter on it for each Zombie card in your graveyard.
Whenever you cast a Zombie spell, create a tapped 2/2 black Zombie creature token.

Swift End

Destroy target creature or planeswalker. You lose 2 life. (Then exile this card. You may cast the creature later from exile.)

Murderous Rider

Lifelink
When Murderous Rider dies, put it on the bottom of its owner's library.

Murderous Rider // Swift End

Endless Ranks of the Dead

At the beginning of your upkeep, create X 2/2 black Zombie creature tokens, where X is half the number of Zombies you control, rounded down.

Stitcher's Supplier

When Stitcher's Supplier enters or dies, mill three cards. (Put the top three cards of your library into your graveyard.)

Accursed Marauder

When Accursed Marauder enters, each player sacrifices a nontoken creature of their choice.

Undead Augur

Whenever Undead Augur or another Zombie you control dies, you draw a card and you lose 1 life.

Vile Entomber

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, search your library for a card, put that card into your graveyard, then shuffle.

Wayward Servant

Whenever another Zombie you control enters, each opponent loses 1 life and you gain 1 life.