Undead Warchief

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

Counterspell

Quest for the Gravelord

Whenever a creature dies, you may put a quest counter on Quest for the Gravelord.
Remove three quest counters from Quest for the Gravelord and sacrifice it: Create a 5/5 black Zombie Giant creature token.

Carrion Feeder

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

Tainted Isle

{T}: Add {C}.
{T}: Add {U} or {B}. Activate only if you control a Swamp.

Lord of the Accursed

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

Profane Insight

You draw a card and you lose 1 life. (Then exile this card. You may cast the creature later from exile.)

Foulmire Knight

Foulmire Knight // Profane Insight

Wayward Servant

Whenever another Zombie you control enters, each opponent loses 1 life and you gain 1 life.

Swamp

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.)

Gleaming Overseer

When Gleaming Overseer enters, amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)
Zombie tokens you control have hexproof and menace.

Compelling Deterrence

Return target nonland permanent to its owner's hand. Then that player discards a card if you control a Zombie.

Yixlid Jailer

Archghoul of Thraben

Whenever Archghoul of Thraben or another Zombie you control dies, look at the top card of your library. If it's a Zombie card, you may reveal it and put it into your hand. If you don't put the card into your hand, you may put it into your graveyard.

Island

Blood Artist

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

Undead Augur

Whenever Undead Augur or another Zombie you control dies, you draw a card and you lose 1 life.

Rakish Crew

When Rakish Crew enters, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."
Whenever an outlaw you control dies, each opponent loses 1 life and you gain 1 life. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)

Lazotep Plating

Amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)
You and permanents you control gain hexproof until end of turn. (You and they can't be the targets of spells or abilities your opponents control.)

Bladestitched Skaab

Fleshbag Marauder

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

Secret Passage

Secret Passage enters tapped.
{T}: Add {U} or {B}.
{4}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Diregraf Captain

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