Humble Defector

{T}: Draw two cards. Target opponent gains control of Humble Defector. Activate only during your turn.

Rakdos Signet

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.)

Clawing Torment

Enchant artifact or creature
As long as enchanted permanent is a creature, it gets -1/-1 and can't block.
Enchanted permanent has "At the beginning of your upkeep, you lose 1 life."

Curse of the Nightly Hunt

Enchant player
Creatures enchanted player controls attack each combat if able.

Curse of Bloodletting

Enchant player
If a source would deal damage to enchanted player, it deals double that damage to that player instead.

Fake Your Own Death

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 and you create a Treasure token." (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Royal Assassin

Morgul-Knife Wound

Enchant creature
Enchanted creature gets -3/-0 and has "At the beginning of your upkeep, exile this creature unless you pay 2 life."

Necromantic Selection

Destroy all creatures, then return a creature card put into a graveyard this way to the battlefield under your control. It's a black Zombie in addition to its other colors and types. Exile Necromantic Selection.

Unhallowed Pact

Enchant creature
When enchanted creature dies, return that card to the battlefield under your control.

Iron Myr

Massacre Girl

Menace
When Massacre Girl enters, each other creature gets -1/-1 until end of turn. Whenever a creature dies this turn, each creature other than Massacre Girl gets -1/-1 until end of turn.

Curse of Hospitality

Enchant player
Creatures attacking enchanted player have trample.
Whenever a creature deals combat damage to enchanted player, that player exiles the top card of their library. Until end of turn, that creature's controller may play that card and they may spend mana as though it were mana of any color to cast that spell.

Bitterheart Witch

Deathtouch
When Bitterheart Witch dies, you may search your library for a Curse card, put it onto the battlefield attached to target player, then shuffle.

Curse of Stalked Prey

Enchant player
Whenever a creature deals combat damage to enchanted player, put a +1/+1 counter on that creature.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Presumed Dead

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield under its owner's control and suspect it." (A suspected creature has menace and can't block.)

Stab Wound

Enchant creature
Enchanted creature gets -2/-2.
At the beginning of the upkeep of enchanted creature's controller, that player loses 2 life.

Abrade

Choose one —
• Abrade deals 3 damage to target creature.
• Destroy target artifact.

Nettlecyst

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1 for each artifact and/or enchantment you control.
Equip {2}

Frontier Warmonger

Whenever one or more creatures attack one of your opponents or a planeswalker they control, those creatures gain menace until end of turn.

Sinister Possession

Enchant creature
Whenever enchanted creature attacks or blocks, its controller loses 2 life.

Leaden Myr

Trespasser's Curse

Enchant player
Whenever a creature enchanted player controls enters, that player loses 1 life and you gain 1 life.

Professor's Warning

Choose one —
• Put a +1/+1 counter on target creature.
• Target creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Burnished Hart

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Ashiok's Reaper

Whenever an enchantment you control is put into a graveyard from the battlefield, draw a card.

Doomwake Giant

Constellation — Whenever Doomwake Giant or another enchantment you control enters, creatures your opponents control get -1/-1 until end of turn.

Rakdos Locket

{T}: Add {B} or {R}.
{B/R}{B/R}{B/R}{B/R}, {T}, Sacrifice Rakdos Locket: Draw two cards.

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."

Kazuul, Tyrant of the Cliffs

Whenever a creature an opponent controls attacks, if you're the defending player, create a 3/3 red Ogre creature token unless that creature's controller pays {3}.

Rakdos Charm

Choose one —
• Exile target player's graveyard.
• Destroy target artifact.
• Each creature deals 1 damage to its controller.

Earthquake

Earthquake deals X damage to each creature without flying and each player.

Bitter Feud

As Bitter Feud enters, choose two players.
If a source controlled by one of the chosen players would deal damage to the other chosen player or a permanent that player controls, that source deals double that damage to that player or permanent instead.

Agent of the Shadow Thieves

Commander creatures you own have "Whenever this creature attacks a player, if no opponent has more life than that player, put a +1/+1 counter on this creature. It gains deathtouch and indestructible until end of turn."

Xantcha, Sleeper Agent

Xantcha, Sleeper Agent enters under the control of an opponent of your choice.
Xantcha attacks each combat if able and can't attack its owner or planeswalkers its owner controls.
{3}: Xantcha's controller loses 2 life and you draw a card. Any player may activate this ability.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Offer Immortality

Target creature gains deathtouch and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Blood Reckoning

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life.

Blightcaster

Whenever you cast an enchantment spell, you may have target creature get -2/-2 until end of turn.

Battle-Rage Blessing

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Deadly Tempest

Destroy all creatures. Each player loses life equal to the number of creatures they controlled that were destroyed this way.

Languish

All creatures get -4/-4 until end of turn.

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Vow of Lightning

Enchant creature
Enchanted creature gets +2/+2, has first strike, and can't attack you or planeswalkers you control.

Armillary Sphere

{2}, {T}, Sacrifice Armillary Sphere: Search your library for up to two basic land cards, reveal them, put them into your hand, then shuffle.