Festering Goblin

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

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Dark Ritual

Chainer's Edict

Target player sacrifices a creature of their choice.
Flashback {5}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Cabal Coffers

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

Undead Warchief

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

Gravecrawler

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

Midnight Reaper

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

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.)

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.

Swamp

Buried Alive

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

Night's Whisper

Barter in Blood

Each player sacrifices two creatures of their choice.

Grotesque Hybrid

Whenever Grotesque Hybrid deals combat damage to a creature, destroy that creature. It can't be regenerated.
Discard a card: Grotesque Hybrid gains flying and protection from green and from white until end of turn.

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.

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature of their choice.

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.

Terror

Destroy target nonartifact, nonblack creature. It can't be regenerated.

Twisted Abomination

{B}: Regenerate Twisted Abomination. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Balthor the Defiled

Minion creatures get +1/+1.
{B}{B}{B}, Exile Balthor the Defiled: Each player returns all black and all red creature cards from their graveyard to the battlefield.

Deathmark Prelate

{2}{B}, {T}, Sacrifice a Zombie: Destroy target non-Zombie creature. It can't be regenerated. Activate only as a sorcery.

Lingering Death

Enchant creature
At the beginning of the end step of enchanted creature's controller, that player sacrifices that creature.

Noxious Ghoul

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