Containment Construct

Whenever you discard a card, you may exile that card from your graveyard. If you do, you may play that card this turn.

Oppression

Whenever a player casts a spell, that player discards a card.

Songs of the Damned

Add {B} for each creature card in your graveyard.

Tinybones, Bauble Burglar

Whenever an opponent discards a card, exile it from their graveyard with a stash counter on it.
During your turn, you may play cards you don't own with stash counters on them from exile, and mana of any type can be spent to cast those spells.
{3}{B}, {T}: Each opponent discards a card. Activate only as a sorcery.

Bottomless Pit

At the beginning of each player's upkeep, that player discards a card at random.

Pilfer

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

Locust Miser

Each opponent's maximum hand size is reduced by two.

Hymn to Tourach

Target player discards two cards at random.

Duress

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

The Rack

As this artifact enters, choose an opponent.
At the beginning of the chosen player's upkeep, this artifact deals X damage to that player, where X is 3 minus the number of cards in their hand.

Mind Rake

Target player discards two cards.
Overload {1}{B} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")