Slithery Stalker

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
When Slithery Stalker enters, exile target green or white creature an opponent controls.
When Slithery Stalker leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Gravegouger

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.

Petravark

When Petravark enters, exile target land.
When Petravark leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Soul Scourge

Flying
When Soul Scourge enters, target player loses 3 life.
When Soul Scourge leaves the battlefield, that player gains 3 life.

Flame Burst

Flame Burst deals X damage to any target, where X is 2 plus the number of cards named Flame Burst in all graveyards.

Mind Rot

Swamp

Enslaved Dwarf

{R}, Sacrifice Enslaved Dwarf: Target black creature gets +1/+0 and gains first strike until end of turn.

Vulturous Aven

Flying
Exploit (When this creature enters, you may sacrifice a creature.)
When Vulturous Aven exploits a creature, you draw two cards and you lose 2 life.

Firebolt

Firebolt deals 2 damage to any target.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mesmeric Fiend

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.

Flaming Gambit

Flaming Gambit deals X damage to target player or planeswalker. That player or that planeswalker's controller may choose a creature they control and have Flaming Gambit deal that damage to it instead.
Flashback {X}{R}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mountain

Rancid Earth

Destroy target land.
Threshold — If seven or more cards are in your graveyard, instead destroy that land and Rancid Earth deals 1 damage to each creature and each player.

Faceless Butcher

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.

Caustic Tar

Enchant land
Enchanted land has "{T}: Target player loses 3 life."

Reave Soul

Destroy target creature with power 3 or less.

Shade's Form

Enchant creature
Enchanted creature has "{B}: This creature gets +1/+1 until end of turn."
When enchanted creature dies, return that card to the battlefield under your control.

Barbarian Outcast

When you control no Swamps, sacrifice Barbarian Outcast.

Temporary Insanity

Untap target creature with power less than the number of cards in your graveyard and gain control of it until end of turn. That creature gains haste until end of turn.

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.

Demolish

Pardic Collaborator

First strike
{B}: Pardic Collaborator gets +1/+1 until end of turn.

Petradon

When Petradon enters, exile two target lands.
When Petradon leaves the battlefield, return the exiled cards to the battlefield under their owners' control.
{R}: Petradon gets +1/+0 until end of turn.

Tainted Peak

{T}: Add {C}.
{T}: Add {B} or {R}. Activate only if you control a Swamp.

Malevolent Awakening

{1}{B}{B}, Sacrifice a creature: Return target creature card from your graveyard to your hand.