When Chittering Rats enters the battlefield, target opponent puts a card from their hand on top of their library.

{T}: Cuombajj Witches deals 1 damage to any target and 1 damage to any target of an opponent's choice.

When Dusk Legion Zealot enters the battlefield, you draw a card and you lose 1 life.

When Gray Merchant of Asphodel enters the battlefield, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)

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

Destroy target nonlegendary creature.

Target creature gets -1/-1 until end of turn for each Swamp you control.

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

Bojuka Bog enters the battlefield tapped. When Bojuka Bog enters the battlefield, exile target player's graveyard. {T}: Add {B}.

({T}: Add {B}.)

Target player sacrifices a creature. Flashback {5}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

{X}: Crypt Rats deals X damage to each creature and each player. Spend only black mana on X.

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

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

{T}, Sacrifice Nihil Spellbomb: Exile target player's graveyard. When Nihil Spellbomb is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

{T}, Sacrifice Nihil Spellbomb: Exile target player's graveyard. When Nihil Spellbomb is put into a graveyard from the battlefield, you may pay {B}. If you do, draw 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 Oubliette enters the battlefield, target creature phases out until Oubliette leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence. {B}: Pestilence deals 1 damage to each creature and each player.

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.)

{T}: Target player exiles a card from their graveyard. {1}, Exile Relic of Progenitus: Exile all graveyards. Draw a card.

Creatures your opponents control get -1/-1 until end of turn. Cycling {2} ({2}, Discard this card: Draw a card.)

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.