Whenever Alley Grifters becomes blocked, defending player discards a card.

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

Flying When Liliana's Specter enters the battlefield, each opponent discards a card.

Ninjutsu {3}{B} ({3}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Whenever Okiba-Gang Shinobi deals combat damage to a player, that player discards two cards.

When Phyrexian Rager enters the battlefield, you draw a card and you lose 1 life.

When Ravenous Rats enters the battlefield, target opponent discards a card.

Barren Moor enters the battlefield tapped. {T}: Add {B}. Cycling {B} ({B}, Discard this card: Draw a card.)

Return target black creature card from your graveyard to your hand. Madness {0} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

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

Target player discards a card. Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)