Divest

Target player reveals their hand. You choose an artifact or creature card from it. That player discards that card.

Confessor

Whenever a player discards a card, you may gain 1 life.

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Drainpipe Vermin

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

Quest for the Nihil Stone

Whenever an opponent discards a card, you may put a quest counter on Quest for the Nihil Stone.
At the beginning of each opponent's upkeep, if that player has no cards in hand and Quest for the Nihil Stone has two or more quest counters on it, you may have that player lose 5 life.

Duress

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