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.

End-Raze Forerunners

Vigilance, trample, haste
When this creature enters, other creatures you control get +2/+2 and gain vigilance and trample until end of turn.

Thelonite Monk

{T}, Sacrifice a green creature: Target land becomes a Forest. (This effect lasts indefinitely.)

Jolrael, Mwonvuli Recluse

Whenever you draw your second card each turn, create a 2/2 green Cat creature token.
{4}{G}{G}: Until end of turn, creatures you control have base power and toughness X/X, where X is the number of cards in your hand.

Breeding Pool

({T}: Add {G} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Shanodin Dryads

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

Collective Restraint

Domain — Creatures can't attack you unless their controller pays {X} for each creature they control that's attacking you, where X is the number of basic land types among lands you control.

Reconnaissance Mission

Whenever a creature you control deals combat damage to a player, you may draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

Song of the Dryads

Enchant permanent
Enchanted permanent is a colorless Forest land.

Arcane Signet

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

Urborg, Tomb of Yawgmoth

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

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. This land deals 1 damage to you.

Vine Dryad

You may exile a green card from your hand rather than pay this spell's mana cost.
Flash
Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)

Mystic Compass

{1}, {T}: Target land becomes the basic land type of your choice until end of turn.

Merfolk Raiders

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
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.)

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Rushwood Dryad

Tolaria West

This land enters tapped.
{T}: Add {U}.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with mana value 0, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Druids' Repository

Whenever a creature you control attacks, put a charge counter on this enchantment.
Remove a charge counter from this enchantment: Add one mana of any color.

Dryad of the Ilysian Grove

You may play an additional land on each of your turns.
Lands you control are every basic land type in addition to their other types.

Bear Umbra

Enchant creature
Enchanted creature gets +2/+2 and has "Whenever this creature attacks, untap all lands you control."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Bayou Dragonfly

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

Mire Boa

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
{G}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Command Tower

Island

Guardian Project

Whenever a nontoken creature you control enters, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Willow Dryad

Forest

Nylea's Presence

Enchant land
When this Aura enters, draw a card.
Enchanted land is every basic land type in addition to its other types.

Crop Rotation

As an additional cost to cast this spell, sacrifice a land.
Search your library for a land card, put that card onto the battlefield, then shuffle.

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Somberwald Dryad

Tideshaper Mystic

{T}: Target land becomes the basic land type of your choice until end of turn. Activate only during your turn.

Deepwood Elder

{X}{G}{G}, {T}, Discard a card: X target lands become Forests until end of turn.

Lush Growth

Enchant land
Enchanted land is a Mountain, Forest, and Plains.

River Boa

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
{G}: Regenerate this creature.

Tanglewalker

Each creature you control can't be blocked as long as defending player controls an artifact land.

Dream Thrush

Flying
{T}: Target land becomes the basic land type of your choice until end of turn.

Marsh Boa

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

Dryad Sophisticate

Nonbasic landwalk (This creature can't be blocked as long as defending player controls a nonbasic land.)

Zodiac Monkey

Vedalken Plotter

When this creature enters, exchange control of target land you control and target land an opponent controls.

Teferi's Veil

Whenever a creature you control attacks, it phases out at end of combat. (While it's phased out, it's treated as though it doesn't exist. It phases in before you untap during your next untap step.)

Tidal Warrior

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

Trailblazer's Boots

Equipped creature has nonbasic landwalk. (It can't be blocked as long as defending player controls a nonbasic land.)
Equip {2}

Sol Ring

Yavimaya Dryad

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
When this creature enters, you may search your library for a Forest card, put it onto the battlefield tapped under target player's control, then shuffle.

Sylvan Scrying

Search your library for a land card, reveal it, put it into your hand, then shuffle.

Overrun

Creatures you control get +3/+3 and gain trample until end of turn. (Each of those creatures can deal excess combat damage to the player or planeswalker it's attacking.)

Grayscaled Gharial

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

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.)

Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Merrow Harbinger

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
When this creature enters, you may search your library for a Merfolk card, reveal it, then shuffle and put that card on top.

Myr Landshaper

{T}: Target land becomes an artifact in addition to its other types until end of turn.

Unstable Frontier

{T}: Add {C}.
{T}: Target land you control becomes the basic land type of your choice until end of turn.

Stonybrook Banneret

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost {1} less to cast.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Coastal Piracy

Whenever a creature you control deals combat damage to an opponent, you may draw a card.

Waterlogged Grove

{T}, Pay 1 life: Add {G} or {U}.
{1}, {T}, Sacrifice this land: Draw a card.

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.

Spreading Seas

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

Flooded Grove

{T}: Add {C}.
{G/U}, {T}: Add {G}{G}, {G}{U}, or {U}{U}.

Biomass Mutation

Creatures you control have base power and toughness X/X until end of turn.

Edric, Spymaster of Trest

Whenever a creature deals combat damage to one of your opponents, its controller may draw a card.

Excavator

{T}, Sacrifice a basic land: Target creature gains landwalk of each of the land types of the sacrificed land until end of turn. (It can't be blocked as long as defending player controls a land of any of those types.)

Reef Shaman

{T}: Target land becomes the basic land type of your choice until end of turn.

Jukai Messenger

Scale Up

Until end of turn, target creature you control becomes a green Wurm with base power and toughness 6/4.
Overload {4}{G}{G} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Rejuvenating Springs

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

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.

Momir Vig, Simic Visionary

Whenever you cast a green creature spell, you may search your library for a creature card, reveal it, then shuffle and put that card on top.
Whenever you cast a blue creature spell, reveal the top card of your library. If it's a creature card, put that card into your hand.

Beastmaster Ascension

Whenever a creature you control attacks, you may put a quest counter on this enchantment.
As long as this enchantment has seven or more quest counters on it, creatures you control get +5/+5.

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Unseen Walker

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
{1}{G}{G}: Target creature gains forestwalk until end of turn.