Unbreathing Horde

Unbreathing Horde enters with a +1/+1 counter on it for each other Zombie you control and each Zombie card in your graveyard.
If Unbreathing Horde would be dealt damage, prevent that damage and remove a +1/+1 counter from it.

Army of the Damned

Create thirteen tapped 2/2 black Zombie creature tokens.
Flashback {7}{B}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

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.)

Fleshbag Marauder

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

Damnation

Destroy all creatures. They can't be regenerated.

Skulking Knight

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
When Skulking Knight becomes the target of a spell or ability, sacrifice it.

Carrion Wurm

Whenever Carrion Wurm attacks or blocks, any player may exile three cards from their graveyard. If a player does, Carrion Wurm assigns no combat damage this turn.

Bad Moon

Soulless One

Soulless One's power and toughness are each equal to the number of Zombies on the battlefield plus the number of Zombie cards in all graveyards.

Call to the Grave

At the beginning of each player's upkeep, that player sacrifices a non-Zombie creature of their choice.
At the beginning of the end step, if no creatures are on the battlefield, sacrifice Call to the Grave.

Undead Warchief

Zombie spells you cast cost {1} less to cast.
Zombie creatures you control get +2/+1.

Grave Titan

Deathtouch
Whenever Grave Titan enters or attacks, create two 2/2 black Zombie creature tokens.

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.

Delirium Skeins

Infectious Horror

Whenever Infectious Horror attacks, each opponent loses 2 life.

Cackling Fiend

When Cackling Fiend enters, each opponent discards a card.

Nested Ghoul

Whenever a source deals damage to Nested Ghoul, create a 2/2 black Phyrexian Zombie creature token.

Vengeful Dead

Whenever Vengeful Dead or another Zombie dies, each opponent loses 1 life.

Noxious Ghoul

Whenever Noxious Ghoul or another Zombie enters, all non-Zombie creatures get -1/-1 until end of turn.

Necrosavant

{3}{B}{B}, Sacrifice a creature: Return Necrosavant from your graveyard to the battlefield. Activate only during your upkeep.

Blind Creeper

Whenever a player casts a spell, Blind Creeper gets -1/-1 until end of turn.

Maggot Carrier

When Maggot Carrier enters, each player loses 1 life.

Walking Corpse

Plague Wind

Destroy all creatures you don't control. They can't be regenerated.

Rotting Fensnake

Severed Legion

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

Yixlid Jailer

Forsaken Wastes

Players can't gain life.
At the beginning of each player's upkeep, that player loses 1 life.
Whenever Forsaken Wastes becomes the target of a spell, that spell's controller loses 5 life.

Twilight's Call

You may cast Twilight's Call as though it had flash if you pay {2} more to cast it. (You may cast it any time you could cast an instant.)
Each player returns all creature cards from their graveyard to the battlefield.