Swamp

Breath of Malfegor

Breath of Malfegor deals 5 damage to each opponent.

Terminate

Destroy target creature. It can't be regenerated.

Blister Beetle

When Blister Beetle enters, target creature gets -1/-1 until end of turn.

Lightning Reaver

Haste; fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever Lightning Reaver deals combat damage to a player, put a charge counter on it.
At the beginning of your end step, Lightning Reaver deals damage equal to the number of charge counters on it to each opponent.

Blood Cultist

{T}: Blood Cultist deals 1 damage to target creature.
Whenever a creature dealt damage by Blood Cultist this turn dies, put a +1/+1 counter on Blood Cultist.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Singe-Mind Ogre

When Singe-Mind Ogre enters, target player reveals a card at random from their hand, then loses life equal to that card's mana value.

Mountain

Blightning

Blightning deals 3 damage to target player or planeswalker. That player or that planeswalker's controller discards two cards.

Leonin Scimitar

Equipped creature gets +1/+1.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Bog Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Cruel Edict

Target opponent sacrifices a creature of their choice.

Dreg Reaver

Viscera Dragger

Cycling {2} ({2}, Discard this card: Draw a card.)
Unearth {1}{B} ({1}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Deathbringer Thoctar

Whenever another creature dies, you may put a +1/+1 counter on Deathbringer Thoctar.
Remove a +1/+1 counter from Deathbringer Thoctar: It deals 1 damage to any target.

Viashino Skeleton

{1}{B}, Discard a card: Regenerate Viashino Skeleton.

Igneous Pouncer

Haste
Swampcycling {2}, mountaincycling {2} ({2}, Discard this card: Search your library for a Swamp or Mountain card, reveal it, put it into your hand, then shuffle.)

Bituminous Blast

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Bituminous Blast deals 4 damage to target creature.

Monstrous Carabid

Monstrous Carabid attacks each combat if able.
Cycling {B/R} ({B/R}, Discard this card: Draw a card.)

Sanity Gnawers

When Sanity Gnawers enters, target player discards a card at random.

Dregscape Zombie

Unearth {B} ({B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)