Call to the Netherworld

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.)

Grave Scrabbler

Madness {1}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)
When Grave Scrabbler enters, if its madness cost was paid, you may return target creature card from a graveyard to its owner's hand.

Archfiend of Spite

Flying
Whenever a source an opponent controls deals damage to Archfiend of Spite, that source's controller loses that much life unless they sacrifice that many permanents.
Madness {3}{B}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Hell Mongrel

Discard a card: Hell Mongrel gets +1/+1 until end of turn.
Madness {2}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Kitchen Imp

Flying, haste
Madness {B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Anje Falkenrath

Haste
{T}, Discard a card: Draw a card.
Whenever you discard a card, if it has madness, untap Anje Falkenrath.

Sign in Blood

Target player draws two cards and loses 2 life.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Asylum Visitor

At the beginning of each player's upkeep, if that player has no cards in hand, you draw a card and you lose 1 life.
Madness {1}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Chainer, Nightmare Adept

Discard a card: You may cast a creature spell from your graveyard this turn. Activate only once each turn.
Whenever a nontoken creature you control enters, if you didn't cast it from your hand, it gains haste until your next turn.

Terminate

Destroy target creature. It can't be regenerated.

Putrid Imp

Discard a card: Putrid Imp gains flying until end of turn.
Threshold — As long as seven or more cards are in your graveyard, Putrid Imp gets +1/+1 and can't block.