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.

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Sol Ring

You Find the Villains' Lair

Choose one —
• Foil Their Scheme — Counter target spell.
• Learn Their Secrets — Draw two cards, then discard two cards.

Make Disappear

Casualty 1 (As you cast this spell, you may sacrifice a creature with power 1 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Counter target spell unless its controller pays {2}.

Day of the Dragons

When this enchantment enters, exile all creatures you control. Then create that many 5/5 red Dragon creature tokens with flying.
When this enchantment leaves the battlefield, sacrifice all Dragons you control. Then return the exiled cards to the battlefield under your control.

Tetsuko Umezawa, Fugitive

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

Resculpt

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

Heraldic Banner

As this artifact enters, choose a color.
Creatures you control of the chosen color get +1/+0.
{T}: Add one mana of the chosen color.

Pull from Tomorrow

Serum Snare

Return target nonland permanent to its owner's hand. If that permanent had mana value 3 or less, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

High Tide

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

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.

Counterspell

Hullbreaker Horror

Flash
This spell can't be countered.
Whenever you cast a spell, choose up to one —
• Return target spell you don't control to its owner's hand.
• Return target nonland permanent to its owner's hand.

Thought Vessel

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

Read the Runes

Draw X cards. For each card drawn this way, discard a card unless you sacrifice a permanent.

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.

Thirst for Meaning

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

Remote Isle

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

Behold the Multiverse

Scry 2, then draw two cards.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

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.

Nadir Kraken

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

Emergence Zone

{T}: Add {C}.
{1}, {T}, Sacrifice this land: You may cast spells this turn as though they had flash.

Engulf the Shore

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

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

Burnished Hart

{3}, Sacrifice this creature: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Reliquary Tower

Drowned Rusalka

{U}, Sacrifice a creature: Discard a card, then draw a card.

Idol of Oblivion

{T}: Draw a card. Activate only if you created a token this turn.
{8}, {T}, Sacrifice this artifact: Create a 10/10 colorless Eldrazi creature token.

Adaptive Automaton

As this creature enters, choose a creature type.
This creature is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Tolarian Winds

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

Abjure

As an additional cost to cast this spell, sacrifice a blue permanent.
Counter target spell.

Borne Upon a Wind

You may cast spells this turn as though they had flash.
Draw a card.

Signal Pest

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
This creature can't be blocked except by creatures with flying or reach.

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. Return it to the battlefield tapped under its owner's control at the beginning of the next end step.

Island

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.

Change of Plans

Each of X target creatures you control connive. You may have any number of them phase out. (To have a creature connive, draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on that creature. Treat phased-out permanents and anything attached to them as though they don't exist until their controller's next turn.)

Lonely Sandbar

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

Ominous Seas

Whenever you draw a card, put a foreshadow counter on this enchantment.
Remove eight foreshadow counters from this enchantment: Create an 8/8 blue Kraken creature token.
Cycling {2} ({2}, Discard this card: Draw a card.)

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.

Perilous Research

Draw two cards, then sacrifice a permanent.

Divide by Zero

Return target spell or permanent with mana value 1 or greater to its owner's hand.
Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Cerulean Wisps

Target creature becomes blue until end of turn. Untap that creature.
Draw a card.

Desert of the Mindful

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

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Frantic Search

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

Ornithopter of Paradise

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 this Siege enters, create two 1/1 blue Kraken creature tokens with trample.

Invasion of Segovia // Caetus, Sea Tyrant of Segovia

Thirst for Discovery

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

Stroke of Genius

Into the Roil

Kicker {1}{U} (You may pay an additional {1}{U} as you cast this spell.)
Return target nonland permanent to its owner's hand. If this spell was kicked, draw a card.

Octavia, Living Thesis

This spell costs {8} less to cast if you have eight or more instant and/or sorcery cards in your graveyard.
Ward {8}
Magecraft — Whenever you cast or copy an instant or sorcery spell, target creature has base power and toughness 8/8 until end of turn.

Sanctum of the Sun

(Transforms from Azor's Gateway.)
{T}: Add X mana of any one color, where X is your life total.

Azor's Gateway

{1}, {T}: Draw a card, then exile a card from your hand. If cards with five or more different mana values are exiled with Azor's Gateway, you gain 5 life, untap Azor's Gateway, and transform it.

Azor's Gateway // Sanctum of the Sun

Thirst for Knowledge

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

Brainstorm

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

Mana Leak

Counter target spell unless its controller pays {3}.

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.

Whelming Wave

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

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

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.)

Dream Fracture

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

Trail of Evidence

Whenever you cast an instant or sorcery spell, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Negate

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.

Censor

Counter target spell unless its controller pays {1}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Flow of Knowledge

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

Haughty Djinn

Flying
Haughty Djinn's power is equal to the number of instant and sorcery cards in your graveyard.
Instant and sorcery spells you cast cost {1} less to cast.