Sangromancer

Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.

Liliana's Specter

Flying
When Liliana's Specter enters, each opponent discards a card.

Bottomless Pit

At the beginning of each player's upkeep, that player discards a card at random.

Rankle, Master of Pranks

Flying, haste
Whenever Rankle, Master of Pranks deals combat damage to a player, choose any number —
• Each player discards a card.
• Each player loses 1 life and draws a card.
• Each player sacrifices a creature of their choice.

Dark Deal

Each player discards all the cards in their hand, then draws that many cards minus one.

Liliana's Caress

Whenever an opponent discards a card, that player loses 2 life.

Geth's Grimoire

Whenever an opponent discards a card, you may draw a card.

Vicious Rumors

Vicious Rumors deals 1 damage to each opponent. Each opponent discards a card, then mills a card. You gain 1 life.

Virus Beetle

When Virus Beetle enters, each opponent discards a card.

Tourach, Dread Cantor

Kicker {B}{B} (You may pay an additional {B}{B} as you cast this spell.)
Protection from white
Whenever an opponent discards a card, put a +1/+1 counter on Tourach, Dread Cantor.
When Tourach enters, if it was kicked, target opponent discards two cards at random.

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

Megrim

Whenever an opponent discards a card, Megrim deals 2 damage to that player.

Elderfang Disciple

When Elderfang Disciple enters, each opponent discards a card.

Bone Miser

Whenever you discard a creature card, create a 2/2 black Zombie creature token.
Whenever you discard a land card, add {B}{B}.
Whenever you discard a noncreature, nonland card, draw a card.

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.)

Fell Specter

Flying
When Fell Specter enters, target opponent discards a card.
Whenever an opponent discards a card, that player loses 2 life.

Necrogoyf

Necrogoyf's power is equal to the number of creature cards in all graveyards.
At the beginning of each player's upkeep, that player discards a card.
Madness {1}{B}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)