The Watcher in the Water

The Watcher in the Water enters tapped with nine stun counters on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Whenever you draw a card during an opponent's turn, create a 1/1 blue Tentacle creature token.
Whenever a Tentacle you control dies, untap up to one target Kraken and put a stun counter on up to one target nonland permanent.

Wonder

Flying
As long as Wonder is in your graveyard and you control an Island, creatures you control have flying.

Nesting Grounds

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

Nezahal, Primal Tide

This spell can't be countered.
You have no maximum hand size.
Whenever an opponent casts a noncreature spell, draw a card.
Discard three cards: Exile Nezahal, Primal Tide. Return it to the battlefield tapped under its owner's control at the beginning of the next end step.

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Reliquary Tower

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

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Lonely Sandbar

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

Ashnod's Altar

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Hylda's Crown of Winter

{1}, {T}: Tap target creature. This ability costs {1} less to activate during your turn.
{3}, Sacrifice Hylda's Crown of Winter: Draw a card for each tapped creature your opponents control.

Thirst for Discovery

Draw three cards. Then discard two cards unless you discard a basic land card.

Sky Diamond

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Negate

Desert of the Mindful

Desert of the Mindful enters tapped.
{T}: Add {U}.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

High Tide

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

Sol Ring

Ledger Shredder

Flying
Whenever a player casts their second spell each turn, Ledger Shredder connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Triskaidekaphile

You have no maximum hand size.
At the beginning of your upkeep, if you have exactly thirteen cards in your hand, you win the game.
{3}{U}: Draw a card.

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

Arcane Signet

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

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Tolarian Winds

Discard all the cards in your hand, then draw that many cards.

Stubborn Denial

Counter target noncreature spell unless its controller pays {1}.
Ferocious — If you control a creature with power 4 or greater, counter that spell instead.

Titan of Littjara

As Titan of Littjara enters, choose a creature type.
Titan of Littjara is the chosen type in addition to its other types.
Whenever Titan of Littjara enters or attacks, you may draw a card for each other creature you control that shares a creature type with it. If you do, discard a card.

Keep Safe

Counter target spell that targets a permanent you control.
Draw a card.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Teferi, Master of Time

You may activate loyalty abilities of Teferi, Master of Time on any player's turn any time you could cast an instant.
+1: Draw a card, then discard a card.
−3: Target creature you don't control phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)
−10: Take two extra turns after this one.

Caetus, Sea Tyrant of Segovia

Noncreature spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting a noncreature spell pays for {1} or one mana of that creature's color.)
At the beginning of your end step, untap up to four target creatures.

Invasion of Segovia

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Segovia enters, create two 1/1 blue Kraken creature tokens with trample.

Invasion of Segovia // Caetus, Sea Tyrant of Segovia

Counterspell

Chasm Skulker

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

Pull from Tomorrow

Misleading Signpost

Flash
When Misleading Signpost enters during the declare attackers step, you may reselect which player or permanent target attacking creature is attacking. (It can't attack its controller or their permanents.)
{T}: Add {U}.

Ever-Watching Threshold

Whenever an opponent attacks, if they attacked you and/or a planeswalker you control, draw a card.

Monstrosity of the Lake

When Monstrosity of the Lake enters, you may pay {5}. If you do, tap all creatures your opponents control, then put a stun counter on each of those creatures. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Islandcycling {2} ({2}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Aetherize

Return all attacking creatures to their owner's hand.

Mystic Sanctuary

({T}: Add {U}.)
Mystic Sanctuary enters tapped unless you control three or more other Islands.
When Mystic Sanctuary enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Thought Reflection

If you would draw a card, draw two cards instead.

Bonders' Enclave

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

Keep Watch

Faerie Mastermind

Flash
Flying
Whenever an opponent draws their second card each turn, you draw a card.
{3}{U}: Each player draws a card.

Meeting of Minds

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Draw two cards.

Throne of Eldraine

As Throne of Eldraine enters, choose a color.
{T}: Add four mana of the chosen color. Spend this mana only to cast monocolored spells of that color.
{3}, {T}: Draw two cards. Spend only mana of the chosen color to activate this ability.

Resculpt

Exile target artifact or creature. Its controller creates a 4/4 blue and red Elemental creature token.

Junk Winder

Affinity for tokens (This spell costs {1} less to cast for each token you control.)
Whenever a token you control enters, tap target nonland permanent an opponent controls. It doesn't untap during its controller's next untap step.

Flow of Knowledge

Draw a card for each Island you control, then discard two cards.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Wash Out

Return all permanents of the color of your choice to their owners' hands.

Dream Fracture

Counter target spell. Its controller draws a card.
Draw a card.

Rapid Hybridization

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

Pongify

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

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Council's Deliberation

Draw a card.
Whenever you scry, if you control an Island, you may exile Council's Deliberation from your graveyard. If you do, draw a card.

Island

Unctus, Grand Metatect

Other blue creatures you control have "Whenever this creature becomes tapped, draw a card, then discard a card."
Other artifact creatures you control get +1/+1.
{U/P}: Until end of turn, target creature you control becomes a blue artifact in addition to its other colors and types. Activate only as a sorcery. ({U/P} can be paid with either {U} or 2 life.)

Ice Out

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
This spell costs {1} less to cast if it's bargained.
Counter target spell.

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

Remote Isle

Remote Isle enters tapped.
{T}: Add {U}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Curse of the Swine

Exile X target creatures. For each creature exiled this way, its controller creates a 2/2 green Boar creature token.

Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Merfolk Looter

Body of Knowledge

Body of Knowledge's power and toughness are each equal to the number of cards in your hand.
You have no maximum hand size.
Whenever Body of Knowledge is dealt damage, draw that many cards.

Even the Score

This spell costs {U}{U}{U} less to cast if an opponent has drawn four or more cards this turn.
Draw X cards.

Nadir Kraken

Whenever you draw a card, you may pay {1}. If you do, put a +1/+1 counter on Nadir Kraken and create a 1/1 blue Tentacle creature token.

Thirst for Knowledge

Draw three cards. Then discard two cards unless you discard an artifact card.

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.

Midnight Clock

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