Swamp

Tomb Hex

Target creature gets -2/-2 until end of turn.
Landfall — If you had a land enter the battlefield under your control this turn, that creature gets -4/-4 until end of turn instead.

Blood Ogre

Bloodthirst 1 (If an opponent was dealt damage this turn, this creature enters with a +1/+1 counter on it.)
First strike (This creature deals combat damage before creatures without first strike.)

Akoum Refuge

Akoum Refuge enters tapped.
When Akoum Refuge enters, you gain 1 life.
{T}: Add {B} or {R}.

Mountain

Bloodfell Caves

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {B} or {R}.

Anathemancer

When Anathemancer enters, it deals damage to target player equal to the number of nonbasic lands that player controls.
Unearth {5}{B}{R} ({5}{B}{R}: 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.)

Sorin's Thirst

Sorin's Thirst deals 2 damage to target creature and you gain 2 life.

Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Fathom Fleet Cutthroat

When Fathom Fleet Cutthroat enters, destroy target creature an opponent controls that was dealt damage this turn.

Doom Blade

Mire's Toll

Target player reveals a number of cards from their hand equal to the number of Swamps you control. You choose one of them. That player discards that card.

Angrath's Marauders

If a source you control would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Deathforge Shaman

Multikicker {R} (You may pay an additional {R} any number of times as you cast this spell.)
When Deathforge Shaman enters, it deals damage to target player or planeswalker equal to twice the number of times it was kicked.

Earth Servant

Earth Servant gets +0/+1 for each Mountain you control.

Gatekeeper of Malakir

Kicker {B} (You may pay an additional {B} as you cast this spell.)
When this creature enters, if it was kicked, target player sacrifices a creature of their choice.

Sun-Crowned Hunters

Enrage — Whenever Sun-Crowned Hunters is dealt damage, it deals 3 damage to target opponent or planeswalker.

Chandra's Outrage

Chandra's Outrage deals 4 damage to target creature and 2 damage to that creature's controller.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Demolish

Battle-Rattle Shaman

At the beginning of combat on your turn, you may have target creature get +2/+0 until end of turn.

Cunning Sparkmage

Haste
{T}: Cunning Sparkmage deals 1 damage to any target.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Touch of Moonglove

Target creature you control gets +1/+0 and gains deathtouch until end of turn. Whenever a creature dealt damage by that creature dies this turn, its controller loses 2 life. (Any amount of damage a creature with deathtouch deals to a creature is enough to destroy it.)

Blood Reckoning

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life.

Quag Sickness

Enchant creature
Enchanted creature gets -1/-1 for each Swamp you control.

Murder

Slavering Nulls

Whenever Slavering Nulls deals combat damage to a player, if you control a Swamp, you may have that player discard a card.

Koth of the Hammer

+1: Untap target Mountain. It becomes a 4/4 red Elemental creature until end of turn. It's still a land.
−2: Add {R} for each Mountain you control.
−5: You get an emblem with "Mountains you control have '{T}: This land deals 1 damage to any target.'"

Mind Rot

Disentomb

Return target creature card from your graveyard to your hand.

Seismic Shift

Destroy target land. Up to two target creatures can't block this turn.

Archfiend of Depravity

Flying
At the beginning of each opponent's end step, that player chooses up to two creatures they control, then sacrifices the rest.

Caress of Phyrexia

Target player draws three cards, loses 3 life, and gets three poison counters.

Urge to Feed

Target creature gets -3/-3 until end of turn. You may tap any number of untapped Vampire creatures you control. If you do, put a +1/+1 counter on each of those Vampires.

Hijack

Gain control of target artifact or creature until end of turn. Untap it. It gains haste until end of turn.

Shimmering Grotto

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Blood Seeker

Whenever a creature an opponent controls enters, you may have that player lose 1 life.