Noxious Ghoul

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

Plains

Anointed Procession

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Thran Dynamo

Corpse Knight

Whenever another creature enters the battlefield under your control, each opponent loses 1 life.

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.

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.)

Swamp

Replication Technique

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it. Players may choose new targets for their copies.)
Create a token that's a copy of target permanent you control.

Sol Ring

Island

Rooftop Storm

You may pay {0} rather than pay the mana cost for Zombie creature spells you cast.

Wayward Servant

Whenever another Zombie enters the battlefield under your control, each opponent loses 1 life and you gain 1 life.

Acererak the Archlich

When Acererak the Archlich enters the battlefield, if you haven't completed Tomb of Annihilation, return Acererak the Archlich to its owner's hand and venture into the dungeon.
Whenever Acererak the Archlich attacks, for each opponent, you create a 2/2 black Zombie creature token unless that player sacrifices a creature.