Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Cabal Pit

{T}: Add {B}. Cabal Pit deals 1 damage to you.
Threshold — {B}, {T}, Sacrifice Cabal Pit: Target creature gets -2/-2 until end of turn. Activate only if seven or more cards are in your graveyard.

Chainer, Dementia Master

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.

Innocent Blood

Each player sacrifices a creature of their choice.

Bog Down

Kicker—Sacrifice two lands. (You may sacrifice two lands in addition to any other costs as you cast this spell.)
Target player discards two cards. If this spell was kicked, that player discards three cards instead.

Duress

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

Haunting Echoes

Exile all cards from target player's graveyard other than basic land cards. For each card exiled this way, search that player's library for all cards with the same name as that card and exile them. Then that player shuffles.

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Engineered Plague

As Engineered Plague enters, choose a creature type.
All creatures of the chosen type get -1/-1.

Yawgmoth's Agenda

You can't cast more than one spell each turn.
You may play lands and cast spells from your graveyard.
If a card would be put into your graveyard from anywhere, exile it instead.

Chainer's Edict

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

Nantuko Shade

{B}: Nantuko Shade gets +1/+1 until end of turn.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Addle

Choose a color. Target player reveals their hand and you choose a card of that color from it. That player discards that card.

Swamp

Slay

Destroy target green creature. It can't be regenerated.
Draw a card.

Corrupt

Corrupt deals damage to any target equal to the number of Swamps you control. You gain life equal to the damage dealt this way.

Mind Sludge

Target player discards a card for each Swamp you control.

Plague Spitter

At the beginning of your upkeep, Plague Spitter deals 1 damage to each creature and each player.
When Plague Spitter dies, it deals 1 damage to each creature and each player.

Coffin Purge

Exile target card from a graveyard.
Flashback {B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)