Megrim

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

Dark Banishing

Destroy target nonblack creature. It can't be regenerated.

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

When Maggot Carrier enters, each player loses 1 life.

Whenever a creature you control deals combat damage to a player, that player discards a card.

Destroy target nonblack creature. It can't be regenerated. You gain life equal to its toughness.

Whenever Deathgazer blocks or becomes blocked by a nonblack creature, destroy that creature at end of combat.

{3}, {T}: Target player discards a card. Activate only during your turn.

Flying
Whenever Abyssal Specter deals damage to a player, that player discards a card.

When Ravenous Rats enters, target opponent discards a card.

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)