Necromancy

You may cast Necromancy as though it had flash. If you cast it any time a sorcery couldn't have been cast, the controller of the permanent it becomes sacrifices it at the beginning of the next cleanup step.
When Necromancy enters, if it's on the battlefield, it becomes an Aura with "enchant creature put onto the battlefield with Necromancy." Put target creature card from a graveyard onto the battlefield under your control and attach Necromancy to it. When Necromancy leaves the battlefield, that creature's controller sacrifices it.

Rain of Filth

Until end of turn, lands you control gain "Sacrifice this land: Add {B}."

Beseech the Mirror

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Search your library for a card, exile it face down, then shuffle. If this spell was bargained, you may cast the exiled card without paying its mana cost if that spell's mana value is 4 or less. Put the exiled card into your hand if it wasn't cast this way.

Saw in Half

Destroy target creature. If that creature dies this way, its controller creates two tokens that are copies of that creature, except their power is half that creature's power and their toughness is half that creature's toughness. Round up each time.

Sacrifice

As an additional cost to cast this spell, sacrifice a creature.
Add an amount of {B} equal to the sacrificed creature's mana value.

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.)

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Beseech the Queen

({2/B} can be paid with any two mana or with {B}. This card's mana value is 6.)
Search your library for a card with mana value less than or equal to the number of lands you control, reveal it, put it into your hand, then shuffle.

Balthor the Defiled

Minion creatures get +1/+1.
{B}{B}{B}, Exile Balthor the Defiled: Each player returns all black and all red creature cards from their graveyard to the battlefield.

Mox Amber

{T}: Add one mana of any color among legendary creatures and planeswalkers you control.

Collective Brutality

Escalate—Discard a card. (Pay this cost for each mode chosen beyond the first.)
Choose one or more —
• Target opponent reveals their hand. You choose an instant or sorcery card from it. That player discards that card.
• Target creature gets -2/-2 until end of turn.
• Target opponent loses 2 life and you gain 2 life.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Final Parting

Search your library for two cards. Put one into your hand and the other into your graveyard. Then shuffle.

Entomb

Search your library for a card, put that card into your graveyard, then shuffle.

Unmarked Grave

Search your library for a nonlegendary card, put that card into your graveyard, then shuffle.

Praetor's Grasp

Search target opponent's library for a card and exile it face down. Then that player shuffles. You may play that card for as long as it remains exiled.

Vilis, Broker of Blood

Flying
{B}, Pay 2 life: Target creature gets -1/-1 until end of turn.
Whenever you lose life, draw that many cards. (Damage causes loss of life.)

Emergence Zone

{T}: Add {C}.
{1}, {T}, Sacrifice Emergence Zone: You may cast spells this turn as though they had flash.

Thoughtseize

Target player reveals their hand. You choose a nonland card from it. That player discards that card. You lose 2 life.

Homeward Path

{T}: Add {C}.
{T}: Each player gains control of all creatures they own.

Dark Petition

Search your library for a card, put that card into your hand, then shuffle.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, add {B}{B}{B}.

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Font of Agonies

Whenever you pay life, put that many blood counters on Font of Agonies.
{1}{B}, Remove four blood counters from Font of Agonies: Destroy target creature.

Fleshwrither

Transfigure {1}{B}{B} ({1}{B}{B}, Sacrifice this creature: Search your library for a creature card with the same mana value as this creature, put that card onto the battlefield, then shuffle. Transfigure only as a sorcery.)

Buried Alive

Search your library for up to three creature cards, put them into your graveyard, then shuffle.

Sidisi, Undead Vizier

Deathtouch
Exploit (When this creature enters, you may sacrifice a creature.)
When Sidisi, Undead Vizier exploits a creature, you may search your library for a card, put it into your hand, then shuffle.

Cut Down

Destroy target creature with total power and toughness 5 or less.

Blood Celebrant

{B}, Pay 1 life: Add one mana of any color.

Opposition Agent

Flash
You control your opponents while they're searching their libraries.
While an opponent is searching their library, they exile each card they find. You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast them.

K'rrik, Son of Yawgmoth

({B/P} can be paid with either {B} or 2 life.)
Lifelink
For each {B} in a cost, you may pay 2 life rather than pay that mana.
Whenever you cast a black spell, put a +1/+1 counter on K'rrik, Son of Yawgmoth.

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

Heartless Summoning

Creature spells you cast cost {2} less to cast.
Creatures you control get -1/-1.

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.