Bottomless Pit

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

Bird

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.

Elderfang Disciple

When this creature enters, each opponent discards a card.

Virus Beetle

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.
When Tourach enters, if it was kicked, target opponent discards two cards at random.

Liliana's Caress

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

Liliana's Specter

Flying
When this creature enters, each opponent discards a card.

The Raven Man

At the beginning of each end step, if a player discarded a card this turn, create a 1/1 black Bird creature token with flying and "This token can't block."
{3}{B}, {T}: Each opponent discards a card. Activate only as a sorcery.

Cunning Lethemancer

At the beginning of your upkeep, each player discards a card.

Raiders' Wake

Whenever an opponent discards a card, that player loses 2 life.
Raid — At the beginning of your end step, if you attacked this turn, target opponent discards a card.

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.)

Skullslither Worm

When this creature enters, each opponent discards a card. For each opponent who can't, put two +1/+1 counters on this creature.

Necrogen Mists

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

Megrim

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

Fell Specter

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