Anurid Brushhopper

Discard two cards: Exile Anurid Brushhopper. Return it to the battlefield under its owner's control at the beginning of the next end step.

Barrier Breach

Exile up to three target enchantments.
Cycling {2} ({2}, Discard this card: Draw a card.)

Armix, Filigree Thrasher

Whenever Armix, Filigree Thrasher attacks, you may discard a card. When you do, target creature defending player controls gets -X/-X until end of turn, where X is the number of artifacts you control plus the number of artifact cards in your graveyard.
Partner (You can have two commanders if both have partner.)

Avenger en-Dal

{2}{W}, {T}, Discard a card: Exile target attacking creature. Its controller gains life equal to its toughness.

Bereavement

Whenever a green creature dies, its controller discards a card.

Voyager Staff

{2}, Sacrifice Voyager Staff: Exile target creature. Return the exiled card to the battlefield under its owner's control at the beginning of the next end step.

Astral Drift

Whenever you cycle Astral Drift or cycle another card while Astral Drift is on the battlefield, you may exile target creature. If you do, return that card to the battlefield under its owner's control at the beginning of the next end step.
Cycling {2}{W} ({2}{W}, Discard this card: Draw a card.)

Cabal Interrogator

{X}{B}, {T}: Target player reveals X cards from their hand and you choose one of them. That player discards that card. Activate only as a sorcery.

Borderland Explorer

When Borderland Explorer enters, each player may discard a card. Each player who discarded a card this way may search their library for a basic land card, reveal it, put it into their hand, then shuffle.

Brain Pry

Choose a nonland card name. Target player reveals their hand. That player discards a card with that name. If they can't, you draw a card.

Kathril, Aspect Warper

When Kathril, Aspect Warper enters, put a flying counter on any creature you control if a creature card in your graveyard has flying. Repeat this process for first strike, double strike, deathtouch, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance. Then put a +1/+1 counter on Kathril for each counter put on a creature this way.

Blackmail

Target player reveals three cards from their hand and you choose one of them. That player discards that card.

Abandon Hope

As an additional cost to cast this spell, discard X cards.
Look at target opponent's hand and choose X cards from it. That player discards those cards.

Burrenton Bombardier

Flying
Reinforce 2—{2}{W} ({2}{W}, Discard this card: Put two +1/+1 counters on target creature.)

Cackling Witch

{X}{B}, {T}, Discard a card: Target creature gets +X/+0 until end of turn.

Cabal Therapy

Choose a nonland card name. Target player reveals their hand and discards all cards with that name.
Flashback—Sacrifice a creature. (You may cast this card from your graveyard for its flashback cost. Then exile it.)