Dread Summons

Each player mills X cards. For each creature card put into a graveyard this way, you create a tapped 2/2 black Zombie creature token. (To mill a card, a player puts the top card of their library into their graveyard.)

Reassembling Skeleton

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

Zombify

Return target creature card from your graveyard to the battlefield.

Massacre Wurm

When this creature enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Swamp

High-Society Hunter

Flying
Whenever this creature attacks, you may sacrifice another creature. If you do, put a +1/+1 counter on this creature.
Whenever another nontoken creature dies, draw a card.

Gatekeeper of Malakir

Kicker {B} (You may pay an additional {B} as you cast this spell.)
When this creature enters, if it was kicked, target player sacrifices a creature of their choice.

Crypt Feaster

Menace (This creature can't be blocked except by two or more creatures.)
Threshold — Whenever this creature attacks, if there are seven or more cards in your graveyard, this creature gets +2/+0 until end of turn.

Tragic Banshee

Morbid — When this creature enters, target creature an opponent controls gets -1/-1 until end of turn. If a creature died this turn, that creature gets -13/-13 instead.

Liliana, Dreadhorde General

Whenever a creature you control dies, draw a card.
+1: Create a 2/2 black Zombie creature token.
−4: Each player sacrifices two creatures of their choice.
−9: Each opponent chooses a permanent they control of each permanent type and sacrifices the rest.

Hero's Downfall

Blasphemous Edict

You may pay {B} rather than pay this spell's mana cost if there are thirteen or more creatures on the battlefield.
Each player sacrifices thirteen creatures of their choice.

Vampiric Rites

{1}{B}, Sacrifice a creature: You gain 1 life and draw a card.

Vampire Gourmand

Whenever this creature attacks, you may sacrifice another creature. If you do, draw a card and this creature can't be blocked this turn.

Midnight Reaper

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

Arbiter of Woe

As an additional cost to cast this spell, sacrifice a creature.
Flying
When this creature enters, each opponent discards a card and loses 2 life. You draw a card and gain 2 life.