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.

Festering Mummy

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

Mausoleum Secrets

Undergrowth — Search your library for a black card with mana value less than or equal to the number of creature cards in your graveyard, reveal it, put it into your hand, then shuffle.

Supernatural Stamina

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Lord of the Accursed

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

Swamp

Bone Splinters

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Walk the Plank

Sword-Point Diplomacy

Reveal the top three cards of your library. For each of those cards, put that card into your hand unless any opponent pays 3 life. Then exile the rest.

Graf Harvest

Zombies you control have menace. (They can't be blocked except by two or more creatures.)
{3}{B}, Exile a creature card from your graveyard: Create a 2/2 black Zombie creature token.

Diregraf Ghoul

Cryptbreaker

{1}{B}, {T}, Discard a card: Create a 2/2 black Zombie creature token.
Tap three untapped Zombies you control: You draw a card and you lose 1 life.

Reassembling Skeleton

{1}{B}: Return this card from your graveyard to the battlefield tapped.

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.)

Grim Haruspex

Morph {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.)
Whenever another nontoken creature you control dies, draw a card.

Bone Picker

This spell costs {3} less to cast if a creature died this turn.
Flying, deathtouch

Vicious Offering

Kicker—Sacrifice a creature. (You may sacrifice a creature in addition to any other costs as you cast this spell.)
Target creature gets -2/-2 until end of turn. If this spell was kicked, that creature gets -5/-5 until end of turn instead.

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.

Immortal Servitude

Return each creature card with mana value X from your graveyard to the battlefield.

Cemetery Recruitment

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

Rancid Rats

Skulk (This creature can't be blocked by creatures with greater power.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Torgaar, Famine Incarnate

As an additional cost to cast this spell, you may sacrifice any number of creatures. This spell costs {2} less to cast for each creature sacrificed this way.
When Torgaar, Famine Incarnate enters, up to one target player's life total becomes half their starting life total, rounded down.