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.

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Grimgrin, Corpse-Born

Grimgrin, Corpse-Born enters tapped and doesn't untap during your untap step.
Sacrifice another creature: Untap Grimgrin and put a +1/+1 counter on it.
Whenever Grimgrin attacks, destroy target creature defending player controls, then put a +1/+1 counter on Grimgrin.

Champion of the Perished

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

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.)

Siren of the Silent Song

Flying
Inspired — Whenever Siren of the Silent Song becomes untapped, each opponent discards a card, then each opponent mills a card.

Gravecrawler

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

Dread Slaver

Whenever a creature dealt damage by Dread Slaver this turn dies, return it to the battlefield under your control. That creature is a black Zombie in addition to its other colors and types.

Jadar, Ghoulcaller of Nephalia

At the beginning of your end step, if you control no creatures with decayed, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

Dark Ritual

Zombie Apocalypse

Return all Zombie creature cards from your graveyard to the battlefield tapped, then destroy all Humans.

Grave Titan

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

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.

Swamp

Diregraf Captain

Deathtouch
Other Zombie creatures you control get +1/+1.
Whenever another Zombie you control dies, target opponent loses 1 life.

Font of Return

{3}{B}, Sacrifice Font of Return: Return up to three target creature cards from your graveyard to your hand.

Gisa, Glorious Resurrector

If a creature an opponent controls would die, exile it instead.
At the beginning of your upkeep, put all creature cards exiled with Gisa, Glorious Resurrector onto the battlefield under your control. They gain decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Liliana of the Dark Realms

+1: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.
−3: Target creature gets +X/+X or -X/-X until end of turn, where X is the number of Swamps you control.
−6: You get an emblem with "Swamps you control have '{T}: Add {B}{B}{B}{B}.'"

Liliana's Talent

Enchant planeswalker
Enchanted planeswalker has "[−8]: Put all creature cards from all graveyards onto the battlefield under your control."
Whenever a creature deals damage to enchanted planeswalker, destroy that creature.

Sol Ring

Wilhelt, the Rotcleaver

Whenever another Zombie you control dies, if it didn't have decayed, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)
At the beginning of your end step, you may sacrifice a Zombie. If you do, draw a card.

Liliana's Reaver

Deathtouch
Whenever Liliana's Reaver deals combat damage to a player, that player discards a card and you create a tapped 2/2 black Zombie creature token.

Draugr Recruiter

Boast — {3}{B}: Return target creature card from your graveyard to your hand. (Activate only if this creature attacked this turn and only once each turn.)

Lord of the Undead

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

Sunken Hollow

({T}: Add {U} or {B}.)
Sunken Hollow enters tapped unless you control two or more basic lands.