Have

Infernal Caretaker

Morph {3}{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.)
When Infernal Caretaker is turned face up, return all Zombie cards from all graveyards to their owners' hands.

Barren Moor

Barren Moor enters the battlefield tapped.
{T}: Add {B}.
Cycling {B} ({B}, Discard this card: Draw a card.)

Ghoulcaller's Chant

Choose one —
• Return target creature card from your graveyard to your hand.
• Return two target Zombie cards from your graveyard to your hand.

Shepherd of Rot

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

Cemetery Recruitment

Return target creature card from your graveyard to your hand. If it's a Zombie card, draw a card.

Festering Mummy

When Festering Mummy dies, you may put a -1/-1 counter on target creature.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters the battlefield, 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.)

Swamp

Gempalm Polluter

Cycling {B}{B} ({B}{B}, Discard this card: Draw a card.)
When you cycle Gempalm Polluter, you may have target player lose life equal to the number of Zombies on the battlefield.

Geth's Verdict

Target player sacrifices a creature and loses 1 life.

Sultai Emissary

When Sultai Emissary dies, manifest the top card of your library. (Put that card onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Sign in Blood

Target player draws two cards and loses 2 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.

Shambling Goblin

When Shambling Goblin dies, target creature an opponent controls gets -1/-1 until end of turn.

Dark Ritual

Gnawing Zombie

{1}{B}, Sacrifice a creature: 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.

Ghoulraiser

When Ghoulraiser enters the battlefield, return a Zombie card at random from your graveyard to your hand.

Nameless Inversion

Changeling (This card is every creature type.)
Target creature gets +3/-3 and loses all creature types until end of turn.