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.

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Castle Garenbrig

This land enters tapped unless you control a Forest.
{T}: Add {G}.
{2}{G}{G}, {T}: Add six {G}. Spend this mana only to cast creature spells or activate abilities of creatures.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Cultivator Colossus

Trample
Cultivator Colossus's power and toughness are each equal to the number of lands you control.
When this creature enters, you may put a land card from your hand onto the battlefield tapped. If you do, draw a card and repeat this process.

Cold-Eyed Selkie

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever this creature deals combat damage to a player, you may draw that many cards.

Vivid Grove

This land enters tapped with two charge counters on it.
{T}: Add {G}.
{T}, Remove a charge counter from this land: Add one mana of any color.

The One Ring

Indestructible
When The One Ring enters, if you cast it, you gain protection from everything until your next turn.
At the beginning of your upkeep, you lose 1 life for each burden counter on The One Ring.
{T}: Put a burden counter on The One Ring, then draw a card for each burden counter on The One Ring.

Joint Exploration

Kicker {G} (You may pay an additional {G} as you cast this spell.)
Scry 2, then draw a card. If this spell was kicked, you may put a land card from your hand onto the battlefield.

Fierce Guardianship

If you control a commander, you may cast this spell without paying its mana cost.
Counter target noncreature spell.

The Monumental Facade

This land enters with two oil counters on it.
{T}: Add {C}.
{T}, Remove an oil counter from this land: Put an oil counter on target artifact or creature you control. Activate only as a sorcery.

Stormtide Leviathan

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.

Sol Ring

Otawara, Soaring City

{T}: Add {U}.
Channel — {3}{U}, Discard this card: Return target artifact, creature, enchantment, or planeswalker to its owner's hand. This ability costs {1} less to activate for each legendary creature you control.

The Flood of Mars

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

Tsunami

Amulet of Vigor

Whenever a permanent you control enters tapped, untap it.

Ghostly Flicker

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

Xolatoyac, the Smiling Flood

Whenever Xolatoyac enters or attacks, put a flood counter on target land. That land is an Island in addition to its other types for as long as it has a flood counter on it.
At the beginning of your end step, untap each permanent you control with a counter on it.

Hall of Storm Giants

If you control two or more other lands, this land enters tapped.
{T}: Add {U}.
{5}{U}: Until end of turn, this land becomes a 7/7 blue Giant creature with ward {3}. It's still a land. (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)

Colossal Whale

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever this creature attacks, you may exile target creature defending player controls until this creature leaves the battlefield. (That creature returns under its owner's control.)

Halimar Depths

This land enters tapped.
When this land enters, look at the top three cards of your library, then put them back in any order.
{T}: Add {U}.

Lingering Mirage

Enchant land
Enchanted land is an Island.
Cycling {2} ({2}, Discard this card: Draw a card.)

Oboro, Palace in the Clouds

{T}: Add {U}.
{1}: Return Oboro to its owner's hand.

Thassa, Deep-Dwelling

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature.
At the beginning of your end step, exile up to one other target creature you control, then return that card to the battlefield under your control.
{3}{U}: Tap another target creature.

Vivid Creek

This land enters tapped with two charge counters on it.
{T}: Add {U}.
{T}, Remove a charge counter from this land: Add one mana of any color.

Typhoon

Typhoon deals damage to each opponent equal to the number of Islands that player controls.

Bounty of the Luxa

At the beginning of your first main phase, remove all flood counters from this enchantment. If no counters were removed this way, put a flood counter on this enchantment and draw a card. Otherwise, add {C}{G}{U}.

Aquitect's Will

Put a flood counter on target land. That land is an Island in addition to its other types for as long as it has a flood counter on it. If you control a Merfolk, draw a card.

Command Beacon

{T}: Add {C}.
{T}, Sacrifice this land: Put your commander into your hand from the command zone.

Worldly Tutor

Search your library for a creature card, reveal it, then shuffle and put the card on top.

Chasm Skulker

Whenever you draw a card, put a +1/+1 counter on this creature.
When this creature dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on this creature. (They can't be blocked as long as defending player controls an Island.)

Dreamroot Cascade

This land enters tapped unless you control two or more other lands.
{T}: Add {G} or {U}.

Omo, Queen of Vesuva

Whenever Omo enters or attacks, put an everything counter on each of up to one target land and up to one target creature.
Each land with an everything counter on it is every land type in addition to its other types.
Each nonland creature with an everything counter on it is every creature type.

Mental Misstep

({U/P} can be paid with either {U} or 2 life.)
Counter target spell with mana value 1.

Up the Beanstalk

When this enchantment enters and whenever you cast a spell with mana value 5 or greater, draw a card.

Vorinclex, Voice of Hunger

Trample
Whenever you tap a land for mana, add one mana of any type that land produced.
Whenever an opponent taps a land for mana, that land doesn't untap during its controller's next untap step.

Drift of Phantasms

Defender (This creature can't attack.)
Flying
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Tidal Warrior

{T}: Target land becomes an Island until end of turn.

Teferi's Time Twist

Exile target permanent you control. Return that card to the battlefield under its owner's control at the beginning of the next end step. If it enters as a creature, it enters with an additional +1/+1 counter on it.

Bonders' Enclave

{T}: Add {C}.
{3}, {T}: Draw a card. Activate only if you control a creature with power 4 or greater.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Force of Will

You may pay 1 life and exile a blue card from your hand rather than pay this spell's mana cost.
Counter target spell.

Mirrodin's Core

{T}: Add {C}.
{T}: Put a charge counter on this land.
{T}, Remove a charge counter from this land: Add one mana of any color.

Faerie Conclave

This land enters tapped.
{T}: Add {U}.
{1}{U}: This land becomes a 2/1 blue Faerie creature with flying until end of turn. It's still a land.

Lurking Predators

Whenever an opponent casts a spell, reveal the top card of your library. If it's a creature card, put it onto the battlefield. Otherwise, you may put that card on the bottom of your library.

Carpet of Flowers

At the beginning of each of your main phases, if you haven't added mana with this ability this turn, you may add X mana of any one color, where X is the number of Islands target opponent controls.

Streambed Aquitects

{T}: Target Merfolk creature gets +1/+1 and gains islandwalk until end of turn. (It can't be blocked as long as defending player controls an Island.)
{T}: Target land becomes an Island until end of turn.

Oracle of Mul Daya

You may play an additional land on each of your turns.
Play with the top card of your library revealed.
You may play lands from the top of your library.

Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Y'shtola Rhul

At the beginning of your end step, exile target creature you control, then return it to the battlefield under its owner's control. Then if it's the first end step of the turn, there is an additional end step after this step.

Planar Incision

Exile target artifact or creature, then return it to the battlefield under its owner's control with a +1/+1 counter on it.

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Littjara Mirrorlake

This land enters tapped.
{T}: Add {U}.
{2}{G}{G}{U}, {T}, Sacrifice this land: Create a token that's a copy of target creature you control, except it enters with an additional +1/+1 counter on it. Activate only as a sorcery.

Flusterstorm

Counter target instant or sorcery spell unless its controller pays {1}.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Rejuvenating Springs

This land enters tapped unless you have two or more opponents.
{T}: Add {G} or {U}.

Desert of the Mindful

This land enters tapped.
{T}: Add {U}.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)

Minamo, School at Water's Edge

{T}: Add {U}.
{U}, {T}: Untap target legendary permanent.

Nesting Grounds

{T}: Add {C}.
{1}, {T}: Move a counter from target permanent you control onto another target permanent. Activate only as a sorcery.

Command Tower

Essence Flux

Exile target creature you control, then return that card to the battlefield under its owner's control. If it's a Spirit, put a +1/+1 counter on it.

Timeless Witness

When this creature enters, return target card from your graveyard to your hand.
Eternalize {5}{G}{G} ({5}{G}{G}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Human Shaman with no mana cost. Eternalize only as a sorcery.)

Eureka Moment

Draw two cards. You may put a land card from your hand onto the battlefield.

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Topiary Stomper

Vigilance (Attacking doesn't cause this creature to tap.)
When this creature enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
This creature can't attack or block unless you control seven or more lands.

Choke

Islands don't untap during their controllers' untap steps.

The Great Henge

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
{T}: Add {G}{G}. You gain 2 life.
Whenever a nontoken creature you control enters, put a +1/+1 counter on it and draw a card.

Ancient Tomb

{T}: Add {C}{C}. This land deals 2 damage to you.

Trenzalore Clocktower

{T}: Add {U}. Put a time counter on Trenzalore Clocktower.
{1}{U}, {T}, Remove twelve time counters from Trenzalore Clocktower and exile it: Shuffle your graveyard and hand into your library, then draw seven cards. Activate only if you control a Time Lord.

Arixmethes, Slumbering Isle

Arixmethes enters tapped with five slumber counters on it.
As long as Arixmethes has a slumber counter on it, it's a land. (It's not a creature.)
Whenever you cast a spell, you may remove a slumber counter from Arixmethes.
{T}: Add {G}{U}.

Lonely Sandbar

This land enters tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Thada Adel, Acquisitor

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Thada Adel deals combat damage to a player, search that player's library for an artifact card and exile it. Then that player shuffles. Until end of turn, you may play that card.

Llanowar Reborn

This land enters tapped.
{T}: Add {G}.
Graft 1 (This land enters with a +1/+1 counter on it. Whenever a creature enters, you may move a +1/+1 counter from this land onto it.)

Blur

Exile target creature you control, then return that card to the battlefield under its owner's control.
Draw a card.

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.

Karn's Bastion

{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Mana Short

Tap all lands target player controls and that player loses all unspent mana.

Boseiju, Who Endures

{T}: Add {G}.
Channel — {1}{G}, Discard this card: Destroy target artifact, enchantment, or nonbasic land an opponent controls. That player may search their library for a land card with a basic land type, put it onto the battlefield, then shuffle. This ability costs {1} less to activate for each legendary creature you control.

Long-Term Plans

Search your library for a card, then shuffle and put that card third from the top.

Marshdrinker Giant

When this creature enters, destroy target Island or Swamp an opponent controls.

Collector Ouphe

Activated abilities of artifacts can't be activated.

Mindbreak Trap

If an opponent cast three or more spells this turn, you may pay {0} rather than pay this spell's mana cost.
Exile any number of target spells.

Spreading Seas

Enchant land
When this Aura enters, draw a card.
Enchanted land is an Island.

Seasinger

When you control no Islands, sacrifice this creature.
You may choose not to untap this creature during your untap step.
{T}: Gain control of target creature whose controller controls an Island for as long as you control this creature and this creature remains tapped.

Blast Zone

This land enters with a charge counter on it.
{T}: Add {C}.
{X}{X}, {T}: Put X charge counters on this land.
{3}, {T}, Sacrifice this land: Destroy each nonland permanent with mana value equal to the number of charge counters on this land.

Forest

Sea's Claim

Enchant land (Target a land as you cast this. This card enters attached to that land.)
Enchanted land is an Island.

Fishliver Oil

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature has islandwalk. (It can't be blocked as long as defending player controls an Island.)

Magosi, the Waterveil

This land enters tapped.
{T}: Add {U}.
{U}, {T}: Put an eon counter on this land. Skip your next turn.
{T}, Remove an eon counter from this land and return it to its owner's hand: Take an extra turn after this one.

Freyalise's Winds

Whenever a permanent becomes tapped, put a wind counter on it.
If a permanent with a wind counter on it would untap during its controller's untap step, remove all wind counters from it instead.

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Hinterland Harbor

This land enters tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.