Duress

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

Wrench Mind

Target player discards two cards unless they discard an artifact card.

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Negate

Gruesome Discovery

Target player discards two cards.
Morbid — If a creature died this turn, instead that player reveals their hand, you choose two cards from it, then that player discards those cards.

Heartless Pillage

Target opponent discards two cards.
Raid — If you attacked this turn, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Wistful Thinking

Target player draws two cards, then discards four cards.

Guul Draz Specter

Flying
Guul Draz Specter gets +3/+3 as long as an opponent has no cards in hand.
Whenever Guul Draz Specter deals combat damage to a player, that player discards a card.

Augur of Skulls

{1}{B}: Regenerate Augur of Skulls.
Sacrifice Augur of Skulls: Target player discards two cards. Activate only during your upkeep.

Terror

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

Counterspell

Divination

Abyssal Nocturnus

Whenever an opponent discards a card, Abyssal Nocturnus gets +2/+2 and gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)