Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Necrogen Mists

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

Sickening Dreams

As an additional cost to cast this spell, discard X cards.
Sickening Dreams deals X damage to each creature and each player.

Tinybones, Trinket Thief

At the beginning of each end step, if an opponent discarded a card this turn, you draw a card and you lose 1 life.
{4}{B}{B}: Each opponent with no cards in hand loses 10 life.

Oppression

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

Skirge Familiar

Bottomless Pit

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