{B}, {T}: Target creature gets -1/-1 until end of turn. Threshold — {3}{B}{B}, {T}: Target creature gets -2/-2 until end of turn. Activate only if seven or more cards are in your graveyard.
Whenever Carrion Rats attacks or blocks, any player may exile a card from their graveyard. If a player does, Carrion Rats assigns no combat damage this turn.
"Just what I need—more competition." —Cabal grave robber
Whenever Carrion Wurm attacks or blocks, any player may exile three cards from their graveyard. If a player does, Carrion Wurm assigns no combat damage this turn.
Since it eats only carrion, sometimes it needs to make some from scratch.
All Nightmares get +1/+1. {B}{B}{B}, Pay 3 life: Put target creature card from a graveyard onto the battlefield under your control. That creature is black and is a Nightmare in addition to its other creature types. When Chainer, Dementia Master leaves the battlefield, exile all Nightmares.
At the beginning of your upkeep, you lose 1 life. At the beginning of your upkeep, you may return target creature card from your graveyard to the battlefield. That creature gains haste until end of turn. Exile it at the beginning of the next end step.
When Faceless Butcher enters, exile another target creature. When Faceless Butcher leaves the battlefield, return the exiled card to the battlefield under its owner's control.
Flying Threshold — As long as seven or more cards are in your graveyard, Gloomdrifter has "When Gloomdrifter enters, nonblack creatures get -2/-2 until end of turn."
When Gravegouger enters, exile up to two target cards from a single graveyard. When Gravegouger leaves the battlefield, return the exiled cards to their owner's graveyard.
Whenever Grotesque Hybrid deals combat damage to a creature, destroy that creature. It can't be regenerated. Discard a card: Grotesque Hybrid gains flying and protection from green and from white until end of turn.
Flying When Hypnox enters, if you cast it from your hand, exile all cards from target opponent's hand. When Hypnox leaves the battlefield, return the exiled cards to their owner's hand.
Haste At the beginning of the end step, sacrifice Ichorid. At the beginning of your upkeep, if Ichorid is in your graveyard, you may exile a black creature card other than Ichorid from your graveyard. If you do, return Ichorid to the battlefield.
When Laquatus's Champion enters, target player loses 6 life. When Laquatus's Champion leaves the battlefield, that player gains 6 life. {B}: Regenerate Laquatus's Champion.
Whenever a permanent other than Last Laugh is put into a graveyard from the battlefield, Last Laugh deals 1 damage to each creature and each player. When no creatures are on the battlefield, sacrifice Last Laugh.
When Mesmeric Fiend enters, target opponent reveals their hand and you choose a nonland card from it. Exile that card. When Mesmeric Fiend leaves the battlefield, return the exiled card to its owner's hand.