Urza's Cave

{T}: Add {C}.
{3}, {T}, Sacrifice Urza's Cave: Search your library for a land card, put it onto the battlefield tapped, then shuffle.

Plains

Yavimaya, Cradle of Growth

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

Acid Rain

Weathered Wayfarer

{W}, {T}: Search your library for a land card, reveal it, put it into your hand, then shuffle. Activate only if an opponent controls more lands than you.

Psychic Venom

Enchant land
Whenever enchanted land becomes tapped, Psychic Venom deals 2 damage to that land's controller.

Mana Geyser

Add {R} for each tapped land your opponents control.

Stern Judge

{T}: Each player loses 1 life for each Swamp they control.

Teferi's Protection

Until your next turn, your life total can't change and you gain protection from everything. All permanents you control phase out. (While they're phased out, they're treated as though they don't exist. They phase in before you untap during your untap step.)
Exile Teferi's Protection.

The Flood of Mars

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Water Always Wins — Whenever The Flood of Mars attacks, put a flood counter on another target creature or land. If it's a creature, it becomes a copy of The Flood of Mars. If it's a land, it becomes an Island in addition to its other types.

Uncontrolled Infestation

Enchant nonbasic land
When enchanted land becomes tapped, destroy it.

Island

Confounding Conundrum

When Confounding Conundrum enters, draw a card.
Whenever a land enters under an opponent's control, if that player had another land enter the battlefield under their control this turn, they return a land they control to its owner's hand.

Kormus Bell

All Swamps are 1/1 black creatures that are still lands.

Boil

Mountain

Temporal Distortion

Whenever a creature or land becomes tapped, put an hourglass counter on it.
Each permanent with an hourglass counter on it doesn't untap during its controller's untap step.
At the beginning of each player's upkeep, remove all hourglass counters from permanents that player controls.

Curse of Marit Lage

When Curse of Marit Lage enters, tap all Islands.
Islands don't untap during their controllers' untap steps.

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

Scald

Whenever a player taps an Island for mana, Scald deals 1 damage to that player.

Flashfires

Burning Earth

Whenever a player taps a nonbasic land for mana, Burning Earth deals 1 damage to that player.

Dream Leash

Enchant permanent
You can't choose an untapped permanent as this spell's target as you cast it.
You control enchanted permanent.

Taniwha

Trample
Phasing (This phases in or out before you untap during each of your untap steps. While it's phased out, it's treated as though it doesn't exist.)
At the beginning of your upkeep, all lands you control phase out. (They phase in before you untap during your next untap step.)

Sunspine Lynx

Players can't gain life.
Damage can't be prevented.
When Sunspine Lynx enters, it deals damage to each player equal to the number of nonbasic lands that player controls.

Crusading Knight

Protection from black
Crusading Knight gets +1/+1 for each Swamp your opponents control.

Tsabo's Web

When Tsabo's Web enters, draw a card.
Each land with an activated ability that isn't a mana ability doesn't untap during its controller's untap step.

Pramikon, Sky Rampart

Flying, defender
As Pramikon, Sky Rampart enters, choose left or right.
Each player may attack only the nearest opponent in the chosen direction and planeswalkers controlled by that opponent.

Lifetap

Whenever a Forest an opponent controls becomes tapped, you gain 1 life.

Expedition Map

{2}, {T}, Sacrifice Expedition Map: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Blood Moon

Pallimud

As Pallimud enters, choose an opponent.
Pallimud's power is equal to the number of tapped lands the chosen player controls.

Winter Moon

Players can't untap more than one nonbasic land during their untap steps.

Lifeblood

Whenever a Mountain an opponent controls becomes tapped, you gain 1 life.

Quicksilver Fountain

At the beginning of each player's upkeep, that player puts a flood counter on target non-Island land they control of their choice. That land is an Island for as long as it has a flood counter on it.
At the beginning of each end step, if all lands on the battlefield are Islands, remove all flood counters from them.

Royal Decree

Cumulative upkeep {W} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever a Swamp, Mountain, black permanent, or red permanent becomes tapped, Royal Decree deals 1 damage to that permanent's controller.

Submerge

If an opponent controls a Forest and you control an Island, you may cast this spell without paying its mana cost.
Put target creature on top of its owner's library.

Chronic Flooding

Enchant land
Whenever enchanted land becomes tapped, its controller mills three cards.

Magus of the Moon

Boiling Seas

Urborg, Tomb of Yawgmoth

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

Mine Layer

{1}{R}, {T}: Put a mine counter on target land.
Whenever a land with a mine counter on it becomes tapped, destroy it.
When Mine Layer leaves the battlefield, remove all mine counters from all lands.

Harbinger of the Seas

Quarum Trench Gnomes

{T}: If target Plains is tapped for mana, it produces colorless mana instead of white mana. (This effect lasts indefinitely.)

Angry Mob

Trample
During your turn, Angry Mob's power and toughness are each equal to 2 plus the number of Swamps your opponents control. During turns other than yours, Angry Mob's power and toughness are each 2.

Ruination

Cyclopean Tomb

{2}, {T}: Put a mire counter on target non-Swamp land. That land is a Swamp for as long as it has a mire counter on it. Activate only during your upkeep.
When Cyclopean Tomb is put into a graveyard from the battlefield, at the beginning of each of your upkeeps for the rest of the game, remove all mire counters from a land that a mire counter was put onto with Cyclopean Tomb but that a mire counter has not been removed from with Cyclopean Tomb.

Sanctimony

Whenever an opponent taps a Mountain for mana, you may gain 1 life.

Karma

At the beginning of each player's upkeep, Karma deals damage to that player equal to the number of Swamps they control.

Steam Vines

Enchant land
When enchanted land becomes tapped, destroy it and Steam Vines deals 1 damage to that land's controller. That player attaches Steam Vines to a land of their choice.