Counterspell

Kitchen

This land enters tapped.
{T}: Add {G} or {U}.
{4}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Spiny Starfish

{U}: Regenerate this creature.
At the beginning of each end step, if this creature regenerated this turn, create a 0/1 blue Starfish creature token for each time it regenerated this turn.

Provisions Merchant

When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Whenever this creature attacks, you may sacrifice a Food. If you do, attacking creatures get +1/+1 and gain trample until end of turn.

Walk the Plank

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.

Deathcap Glade

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

Deepglow Skate

When this creature enters, double the number of each kind of counter on any number of target permanents.

Bloodtithe Collector

Flying
When this creature enters, if an opponent lost life this turn, each opponent discards a card.

Tanglepool Bridge

This land enters tapped.
Indestructible
{T}: Add {G} or {U}.

Adrix and Nev, Twincasters

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
If one or more tokens would be created under your control, twice that many of those tokens are created instead.

Haywire Mite

When this creature dies, you gain 2 life.
{G}, Sacrifice this creature: Exile target noncreature artifact or noncreature enchantment.

Llanowar Wastes

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

Lush Oasis

This land enters tapped.
When this land enters, it deals 1 damage to target opponent.
{T}: Add {G} or {U}.

Spinning Wheel Kick

Target creature you control deals damage equal to its power to each of X target creatures and/or planeswalkers.

Command Tower

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

Opulent Palace

This land enters tapped.
{T}: Add {B}, {G}, or {U}.

Bioshift

Move any number of +1/+1 counters from target creature onto another target creature with the same controller.

Song of Eärendil

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Scry 2, then draw two cards.
II — Create a Treasure token and a 2/2 blue Bird creature token with flying.
III — Put a flying counter on each creature you control without flying.

Grothama, All-Devouring

Other creatures have "Whenever this creature attacks, you may have it fight Grothama, All-Devouring."
When Grothama leaves the battlefield, each player draws cards equal to the amount of damage dealt to Grothama this turn by sources they controlled.

Dark Ritual

Clinging Anemones

Defender
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Zagoth Triome

({T}: Add {B}, {G}, or {U}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Fetid Pools

({T}: Add {U} or {B}.)
This land enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Novijen, Heart of Progress

{T}: Add {C}.
{G}{U}, {T}: Put a +1/+1 counter on each creature that entered this turn.

Coral Reef

This enchantment enters with four polyp counters on it.
Sacrifice an Island: Put two polyp counters on this enchantment.
{U}, Tap an untapped blue creature you control, Remove a polyp counter from this enchantment: Put a +0/+1 counter on target creature.

Dismal Backwater

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

Chatterfang, Squirrel General

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
If one or more tokens would be created under your control, those tokens plus that many 1/1 green Squirrel creature tokens are created instead.
{B}, Sacrifice X Squirrels: Target creature gets +X/-X until end of turn.

Xavier Sal, Infested Captain

{T}, Remove a counter from another permanent you control: Populate. Activate only as a sorcery. (Create a token that's a copy of a creature token you control.)
{T}, Sacrifice another creature: Proliferate. Activate only as a sorcery. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Dimir Guildgate

This land enters tapped.
{T}: Add {U} or {B}.

Cynette, Jelly Drover

When Cynette enters or dies, create a 1/1 blue Jellyfish creature token with flying.
Creatures you control with flying get +1/+1.

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.

Breeding Pool

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

Walking Sponge

{T}: Target creature loses your choice of flying, first strike, or trample until end of turn.

Arvinox, the Mind Flail

Arvinox isn't a creature unless you control three or more permanents you don't own.
At the beginning of your end step, exile the bottom card of each opponent's library face down. For as long as those cards remain exiled, you may look at them, you may cast permanent spells from among them, and you may spend mana as though it were mana of any color to cast those spells.

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.

Blood Tithe

Each opponent loses 3 life. You gain life equal to the life lost this way.

Choked Estuary

As this land enters, you may reveal an Island or Swamp card from your hand. If you don't, this land enters tapped.
{T}: Add {U} or {B}.

Island

Homarid Spawning Bed

{1}{U}{U}, Sacrifice a blue creature: Create X 1/1 blue Camarid creature tokens, where X is the sacrificed creature's mana value.

Mind Flayer

Dominate Monster — When this creature enters, gain control of target creature for as long as you control this creature.

King Crab

{1}{U}, {T}: Put target green creature on top of its owner's library.

Sol Ring

Dreamroot Cascade

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

Flooded Grove

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

Thought Vessel

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

Homarid Warrior

{U}: This creature gains shroud until end of turn and doesn't untap during your next untap step. Tap it. (A creature with shroud can't be the target of spells or abilities.)

Temple of Mystery

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {G} or {U}.

Blooming Marsh

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

Puffer Extract

{X}, {T}: Target creature you control gets +X/+X until end of turn. Destroy it at the beginning of the next end step.

Stinging Lionfish

Whenever you cast your first spell during each opponent's turn, you may tap or untap target nonland permanent.

Dimir Aqueduct

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Forest

Contaminated Aquifer

({T}: Add {U} or {B}.)
This land enters tapped.

Cephalid Aristocrat

Whenever this creature becomes the target of a spell or ability, mill two cards.

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Pursued Whale

When this creature enters, each opponent creates a 1/1 red Pirate creature token with "This token can't block" and "Creatures you control attack each combat if able."
Spells your opponents cast that target this creature cost {3} more to cast.

Simic Growth Chamber

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Plagon, Lord of the Beach

When Plagon enters, draw a card for each creature you control with toughness greater than its power.
{W/U}: Target creature you control assigns combat damage equal to its toughness rather than its power this turn.

Darkwater Catacombs

Confiscate

Enchant permanent
You control enchanted permanent.

Drain the Well

Darkslick Shores

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

Darkmoss Bridge

This land enters tapped.
Indestructible
{T}: Add {B} or {G}.

Brine Giant

Affinity for enchantments (This spell costs {1} less to cast for each enchantment you control.)

Necroblossom Snarl

As this land enters, you may reveal a Swamp or Forest card from your hand. If you don't, this land enters tapped.
{T}: Add {B} or {G}.

Gyome, Master Chef

Trample
At the beginning of your end step, create a number of Food tokens equal to the number of nontoken creatures you had enter under your control this turn.
{1}, Sacrifice a Food: Target creature gains indestructible until end of turn. Tap it.

Foreboding Landscape

{T}: Add {C}.
{T}, Sacrifice this land: Search your library for a basic Swamp, Forest, or Island card, put it onto the battlefield tapped, then shuffle.
Cycling {B}{G}{U} ({B}{G}{U}, Discard this card: Draw a card.)

Hedge Maze

({T}: Add {G} or {U}.)
This land enters tapped.
When this land enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Sigiled Starfish

{T}: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Academy Ruins

{T}: Add {C}.
{1}{U}, {T}: Put target artifact card from your graveyard on top of your library.

Hinterland Harbor

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

Concession Stand

Visit — Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Old Man of the Sea

You may choose not to untap this creature during your untap step.
{T}: Gain control of target creature with power less than or equal to this creature's power for as long as this creature remains tapped and that creature's power remains less than or equal to this creature's power.

Midnight Clock

{T}: Add {U}.
{2}{U}: Put an hour counter on this artifact.
At the beginning of each upkeep, put an hour counter on this artifact.
When the twelfth hour counter is put on this artifact, shuffle your hand and graveyard into your library, then draw seven cards. Exile this artifact.

Fellwar Stone

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

Rejuvenating Springs

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

Yorvo, Lord of Garenbrig

Yorvo enters with four +1/+1 counters on it.
Whenever another green creature you control enters, put a +1/+1 counter on Yorvo. Then if that creature's power is greater than Yorvo's power, put another +1/+1 counter on Yorvo.

Tishana, Voice of Thunder

Tishana's power and toughness are each equal to the number of cards in your hand.
You have no maximum hand size.
When Tishana enters, draw a card for each creature you control.

Spectral Sailor

Flash (You may cast this spell any time you could cast an instant.)
Flying
{3}{U}: Draw a card.

Duress

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Hydroid Krasis

When you cast this spell, you gain half X life and draw half X cards. Round down each time.
Flying, trample
This creature enters with X +1/+1 counters on it.

Tail the Suspect

Investigate. You may play an additional land this turn. (Then exile this card. You may cast the creature later from exile.)

Kellan, Inquisitive Prodigy

Flying, vigilance
Whenever Kellan attacks, destroy up to one target artifact. If you controlled that permanent, draw a card.

Kellan, Inquisitive Prodigy // Tail the Suspect

Merseine

Enchant creature
This Aura enters with three net counters on it.
Enchanted creature doesn't untap during its controller's untap step if this Aura has a net counter on it.
Pay enchanted creature's mana cost: Remove a net counter from this Aura. Only the controller of the enchanted creature may activate this ability.

Octopus Umbra

Enchant creature
Enchanted creature has base power and toughness 8/8 and has "Whenever this creature attacks, you may tap target creature with power 8 or less."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Homarid Shaman

Golgari Rot Farm

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {B}{G}.

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.

Thrasios, Triton Hero

{4}: Scry 1, then reveal the top card of your library. If it's a land card, put it onto the battlefield tapped. Otherwise, draw a card.
Partner (You can have two commanders if both have partner.)

Zegana, Utopian Speaker

When Zegana enters, if you control another creature with a +1/+1 counter on it, draw a card.
{4}{G}{U}: Adapt 4. (If this creature has no +1/+1 counters on it, put four +1/+1 counters on it.)
Each creature you control with a +1/+1 counter on it has trample.

Vorel of the Hull Clade

{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.

Abundant Harvest

Choose land or nonland. Reveal cards from the top of your library until you reveal a card of the chosen kind. Put that card into your hand and the rest on the bottom of your library in a random order.

Breaching Hippocamp

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, untap another target creature you control.

Skullcap Snail

When this creature enters, target opponent exiles a card from their hand.

Drowned Catacomb

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

Killer Service

When this enchantment enters, create a number of Food tokens equal to the number of opponents you have. (They're artifacts with "{2}, {T}, Sacrifice this token: You gain 3 life.")
At the beginning of your end step, you may pay {2} and sacrifice a token. If you do, create a 4/4 green Rhino Warrior creature token.

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")