Sacrifice Play

A person outside the game chooses an attacking or blocking creature target opponent controls. That player sacrifices that creature.

Fork

Copy target instant or sorcery spell, except that the copy is red. You may choose new targets for the copy.

Disciple of Grace

Protection from black
Cycling {2} ({2}, Discard this card: Draw a card.)

Kambal, Consul of Allocation

Whenever an opponent casts a noncreature spell, that player loses 2 life and you gain 2 life.

Black Knight

First strike (This creature deals combat damage before creatures without first strike.)
Protection from white (This creature can't be blocked, targeted, dealt damage, or enchanted by anything white.)

Ayara, First of Locthwain

Whenever Ayara, First of Locthwain or another black creature you control enters, each opponent loses 1 life and you gain 1 life.
{T}, Sacrifice another black creature: Draw a card.

Knight of Malice

First strike (This creature deals combat damage before creatures without first strike.)
Hexproof from white (This creature can't be the target of white spells or abilities your opponents control.)
This creature gets +1/+0 as long as any player controls a white permanent.

Giant's Skewer

Equipped creature gets +2/+1.
Whenever equipped creature deals combat damage to a creature, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Disciple of Malice

Protection from white
Cycling {2} ({2}, Discard this card: Draw a card.)

Darien, King of Kjeldor

Whenever you're dealt damage, you may create that many 1/1 white Soldier creature tokens.

Sneak Attack

{R}: You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice the creature at the beginning of the next end step.

White Knight

First strike (This creature deals combat damage before creatures without first strike.)
Protection from black (This creature can't be blocked, targeted, dealt damage, or enchanted by anything black.)

Predator's Gambit

Enchant creature
Enchanted creature gets +2/+1.
Enchanted creature has intimidate as long as its controller controls no other creatures. (It can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Linden, the Steadfast Queen

Vigilance (Attacking doesn't cause this creature to tap.)
Whenever a white creature you control attacks, you gain 1 life.

Skewer the Critics

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Skewer the Critics deals 3 damage to any target.

Shield Mare

Shield Mare can't be blocked by red creatures.
When Shield Mare enters or becomes the target of a spell or ability an opponent controls, you gain 3 life.

Plague Mare

Plague Mare can't be blocked by white creatures.
When Plague Mare enters, creatures your opponents control get -1/-1 until end of turn.

Bishop of the Bloodstained

When Bishop of the Bloodstained enters, target opponent loses 1 life for each Vampire you control.

King Macar, the Gold-Cursed

Inspired — Whenever King Macar, the Gold-Cursed becomes untapped, you may exile target creature. If you do, create a Gold token. (It's an artifact with "Sacrifice this artifact: Add one mana of any color.")

Rank and File

When Rank and File enters, green creatures get -1/-1 until end of turn.

Battlefield Promotion

Put a +1/+1 counter on target creature. That creature gains first strike until end of turn. You gain 2 life. (A creature with first strike deals combat damage before creatures without first strike.)

Captured by the Consulate

Enchant creature you don't control
Enchanted creature can't attack.
Whenever an opponent casts a spell, if it has a single target, change the target to enchanted creature if able.

Queen Marchesa

Deathtouch, haste
When Queen Marchesa enters, you become the monarch.
At the beginning of your upkeep, if an opponent is the monarch, create a 1/1 black Assassin creature token with deathtouch and haste.

Knight of Grace

First strike (This creature deals combat damage before creatures without first strike.)
Hexproof from black (This creature can't be the target of black spells or abilities your opponents control.)
This creature gets +1/+0 as long as any player controls a black permanent.

Divine Gambit

Exile target artifact, creature, or enchantment an opponent controls. That player may put a permanent card from their hand onto the battlefield.

Bishop of Rebirth

Vigilance
Whenever Bishop of Rebirth attacks, you may return target creature card with mana value 3 or less from your graveyard to the battlefield.

King's Assassin

{T}: Destroy target tapped creature. Activate only during your turn, before attackers are declared.

Blood Clock

At the beginning of each player's upkeep, that player returns a permanent they control to its owner's hand unless they pay 2 life.

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.