Grim Haruspex

Morph {B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
Whenever another nontoken creature you control dies, draw a card.

Zombie Master

Other Zombie creatures have swampwalk. (They can't be blocked as long as defending player controls a Swamp.)
Other Zombies have "{B}: Regenerate this permanent."

The Scarab God

At the beginning of your upkeep, each opponent loses X life and you scry X, where X is the number of Zombies you control.
{2}{U}{B}: Exile target creature card from a graveyard. Create a token that's a copy of it, except it's a 4/4 black Zombie.
When The Scarab God dies, return it to its owner's hand at the beginning of the next end step.

Undead Warchief

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

Lord of the Undead

Other Zombie creatures get +1/+1.
{1}{B}, {T}: Return target Zombie card from your graveyard to your hand.

Noxious Ghoul

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

Fallen Shinobi

Ninjutsu {2}{U}{B} ({2}{U}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Fallen Shinobi deals combat damage to a player, that player exiles the top two cards of their library. Until end of turn, you may play those cards without paying their mana costs.

Plague Belcher

Menace
When Plague Belcher enters, put two -1/-1 counters on target creature you control.
Whenever another Zombie you control dies, each opponent loses 1 life.

Ghoulcaller Gisa

{B}, {T}, Sacrifice another creature: Create X 2/2 black Zombie creature tokens, where X is the sacrificed creature's power.

Vengeful Dead

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

Gravespawn Sovereign

Tap five untapped Zombies you control: Put target creature card from a graveyard onto the battlefield under your control.

Geralf, Visionary Stitcher

Zombies you control have flying.
{U}, {T}, Sacrifice another nontoken creature: Create an X/X blue Zombie creature token, where X is the sacrificed creature's toughness.

Tainted Adversary

Deathtouch
When Tainted Adversary enters, you may pay {2}{B} any number of times. When you pay this cost one or more times, put that many +1/+1 counters on Tainted Adversary, then create twice that many 2/2 black Zombie creature tokens with decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Gravecrawler

Gravecrawler can't block.
You may cast Gravecrawler from your graveyard as long as you control a Zombie.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)