Megrim

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

Damnable Pact

Target player draws X cards and loses X life.

At the beginning of each player's draw step, that player draws two additional cards.

Flying
Whenever Hypnotic Specter deals damage to an opponent, that player discards a card at random.

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.

Target creature gets -X/-X until end of turn, where X is 7 minus the number of cards in that creature's controller's hand.

When Ravenous Rats enters the battlefield, target opponent discards a card.

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

Destroy target creature. Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

When Drainpipe Vermin dies, you may pay {B}. If you do, target player discards a card.

Whenever Howling Golem attacks or blocks, each player draws a card.

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.