Writhing Necromass

This spell costs {1} less to cast for each creature card in your graveyard.
Deathtouch

Necropolis Fiend

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Flying
{X}, {T}, Exile X cards from your graveyard: Target creature gets -X/-X until end of turn.

Consume Spirit

Spend only black mana on X.
Consume Spirit deals X damage to any target and you gain X life.

Bond of Agony

As an additional cost to cast this spell, pay X life.
Each other player loses X life.

Ancient Stone Idol

Flash
This spell costs {1} less to cast for each attacking creature.
Trample
When Ancient Stone Idol dies, create a 6/12 colorless Construct artifact creature token with trample.

Drain Life

Spend only black mana on X.
Drain Life deals X damage to any target. You gain life equal to the damage dealt, but not more life than the player's life total before the damage was dealt, the planeswalker's loyalty before the damage was dealt, or the creature's toughness.

Shadow of Mortality

If your life total is less than your starting life total, this spell costs {X} less to cast, where X is the difference.

Profane Command

Choose two —
• Target player loses X life.
• Return target creature card with mana value X or less from your graveyard to the battlefield.
• Target creature gets -X/-X until end of turn.
• Up to X target creatures gain fear until end of turn. (They can't be blocked except by artifact creatures and/or black creatures.)

Soul Burn

Spend only black and/or red mana on X.
Soul Burn deals X damage to any target. You gain life equal to the damage dealt, but not more than the amount of {B} spent on X, the player's life total before the damage was dealt, the planeswalker's loyalty before the damage was dealt, or the creature's toughness.

Marshmist Titan

This spell costs {X} less to cast, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Gorex, the Tombshell

As an additional cost to cast this spell, you may exile any number of creature cards from your graveyard. This spell costs {2} less to cast for each card exiled this way.
Deathtouch
Whenever Gorex, the Tombshell attacks or dies, choose a card at random exiled with Gorex and put that card into its owner's hand.

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Sibsig Muckdraggers

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
When Sibsig Muckdraggers enters, return target creature card from your graveyard to your hand.

Death-Rattle Oni

Flash
This spell costs {2} less to cast for each creature that died this turn.
When Death-Rattle Oni enters, destroy all other creatures that were dealt damage this turn.

Tombstalker

Flying
Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)

Sojourner's Companion

Affinity for artifacts
Artifact landcycling {2} ({2}, Discard this card: Search your library for an artifact land card, reveal it, put it into your hand, then shuffle.)

Illuminor Szeras

Secrets of the Soul — {T}, Sacrifice another creature: Add an amount of {B} equal to the sacrificed creature's mana value.

Damnable Pact

Target player draws X cards and loses X life.

Bone Picker

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

Myr Enforcer

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)

Liliana's Indignation

Mill X cards. Target player loses 2 life for each creature card put into your graveyard this way.

Torment of Hailfire

Repeat the following process X times. Each opponent loses 3 life unless that player sacrifices a nonland permanent of their choice or discards a card.

Shambling Attendants

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
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.

Gurmag Angler

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)