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.

Mountain

Tainted Peak

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

Demolish

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.

Barbarian Outcast

When you control no Swamps, sacrifice this creature.

Petravark

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

Mesmeric Fiend

When this creature enters, target opponent reveals their hand and you choose a nonland card from it. Exile that card.
When this creature leaves the battlefield, return the exiled card to its owner's hand.

Faceless Butcher

When this creature enters, exile another target creature.
When this creature leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Malevolent Awakening

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

Swamp

Petradon

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

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.)

Slithery Stalker

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

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.

Soul Scourge

Flying
When this creature enters, target player loses 3 life.
When this creature leaves the battlefield, that player gains 3 life.

Pardic Collaborator

First strike
{B}: This creature gets +1/+1 until end of turn.

Caustic Tar

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

Enslaved Dwarf

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

Gravegouger

When this creature enters, exile up to two target cards from a single graveyard.
When this creature leaves the battlefield, return the exiled cards to their owner's graveyard.

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.

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 leaves the battlefield, exile all Nightmares.

Pyromania

{1}{R}, Discard a card at random: This enchantment deals 1 damage to any target.
{1}{R}, Sacrifice this enchantment: It deals 1 damage to any target.