Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Living Death

Each player exiles all creature cards from their graveyard, then sacrifices all creatures they control, then puts all cards they exiled this way onto the battlefield.

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

Noxious Ghoul

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

Zombie Apocalypse

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

Open the Graves

Whenever a nontoken creature you control dies, create a 2/2 black Zombie creature token.

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.

Grave Titan

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

Lord of the Accursed

Other Zombies you control get +1/+1.
{1}{B}, {T}: All Zombies gain menace until end of turn.

Undead Warchief

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

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.

Tragic Slip

Target creature gets -1/-1 until end of turn.
Morbid — That creature gets -13/-13 until end of turn instead if a creature died this turn.

Midnight Reaper

Whenever a nontoken creature you control dies, this creature deals 1 damage to you and you draw a card.

Tattered Mummy

When Tattered Mummy dies, each opponent loses 2 life.

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.)

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

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.

Malakir Mire

Malakir Mire enters tapped.
{T}: Add {B}.

Malakir Rebirth

Choose target creature. You lose 2 life. Until end of turn, that creature gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Malakir Rebirth // Malakir Mire

Doomed Dissenter

When Doomed Dissenter dies, create a 2/2 black Zombie creature token.

Buried Alive

Search your library for up to three creature cards, put them into your graveyard, then shuffle.

Spark Harvest

As an additional cost to cast this spell, sacrifice a creature or pay {3}{B}.
Destroy target creature or planeswalker.

Sidisi, Undead Vizier

Deathtouch
Exploit (When this creature enters, you may sacrifice a creature.)
When Sidisi, Undead Vizier exploits a creature, you may search your library for a card, put it into your hand, then shuffle.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Victimize

Choose two target creature cards in your graveyard. Sacrifice a creature. If you do, return the chosen cards to the battlefield tapped.

Shepherd of Rot

{T}: Each player loses 1 life for each Zombie on the battlefield.

Relentless Dead

Menace (This creature can't be blocked except by two or more creatures.)
When Relentless Dead dies, you may pay {B}. If you do, return it to its owner's hand.
When Relentless Dead dies, you may pay {X}. If you do, return another target Zombie creature card with mana value X from your graveyard to the battlefield.

Hero's Downfall

Festering Goblin

When Festering Goblin dies, target creature gets -1/-1 until end of turn.

Songs of the Damned

Add {B} for each creature card in your graveyard.

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."

Gravecrawler

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

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Fleshbag Marauder

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

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.

Crypt of Agadeem

Crypt of Agadeem enters tapped.
{T}: Add {B}.
{2}, {T}: Add {B} for each black creature card in your graveyard.