Thought Vessel

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

Brainstorm

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

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.

Shark Typhoon

Whenever you cast a noncreature spell, create an X/X blue Shark creature token with flying, where X is that spell's mana value.
Cycling {X}{1}{U} ({X}{1}{U}, Discard this card: Draw a card.)
When you cycle this card, create an X/X blue Shark creature token with flying.

Archaeomancer

When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Flow of Ideas

Three Steps Ahead

Spree (Choose one or more additional costs.)
+ {1}{U} — Counter target spell.
+ {3} — Create a token that's a copy of target artifact or creature you control.
+ {2} — Draw two cards, then discard 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.

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.

Temporal Manipulation

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.

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.

Flow of Knowledge

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

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Lórien Revealed

Draw three cards.
Islandcycling {1} ({1}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Rapid Hybridization

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

Rewind

Counter target spell. Untap up to four lands.

Time Warp

Target player takes an extra turn after this one.

Displacer Kitten

Avoidance — Whenever you cast a noncreature spell, exile up to one target nonland permanent you control, then return that card to the battlefield under its owner's control.

Mindsplice Apparatus

Flash
At the beginning of your upkeep, put an oil counter on this artifact.
Instant and sorcery spells you cast cost {1} less to cast for each oil counter on this artifact.

Engulf the Shore

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

Extraplanar Lens

Imprint — When this artifact enters, you may exile target land you control.
Whenever a land with the same name as the exiled card is tapped for mana, its controller adds one mana of any type that land produced.

Rhystic Study

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

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Omniscience

You may cast spells from your hand without paying their mana costs.

Primal Wellspring

(Transforms from Primal Amulet.)
{T}: Add one mana of any color. When that mana is spent to cast an instant or sorcery spell, copy that spell and you may choose new targets for the copy.

Primal Amulet

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, put a charge counter on this artifact. Then if there are four or more charge counters on it, you may remove those counters and transform it.

Primal Amulet // Primal Wellspring

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Eluge, the Shoreless Sea

Eluge's power and toughness are each equal to the number of Islands you control.
Whenever Eluge enters or attacks, put a flood counter on target land. It's an Island in addition to its other types for as long as it has a flood counter on it.
The first instant or sorcery spell you cast each turn costs {U} (or {1}) less to cast for each land you control with a flood counter on it.

Archmage Emeritus

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

Pull from Tomorrow

Soporific Springs

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}.

Sink into Stupor

Return target spell or nonland permanent an opponent controls to its owner's hand.

Sink into Stupor // Soporific Springs

Isochron Scepter

Imprint — When this artifact enters, you may exile an instant card with mana value 2 or less from your hand.
{2}, {T}: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

Capture of Jingzhou

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
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.)

Jace, Wielder of Mysteries

If you would draw a card while your library has no cards in it, you win the game instead.
+1: Target player mills two cards. Draw a card.
−8: Draw seven cards. Then if your library has no cards in it, you win the game.

Archmage's Charm

Choose one —
• Counter target spell.
• Target player draws two cards.
• Gain control of target nonland permanent with mana value 1 or less.

High Tide

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

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.

Blue Sun's Zenith

Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.

Spectral Deluge

Return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.
Foretell {1}{U}{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.)

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.

Counterspell

Scourge of Fleets

When this creature enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Wavebreak Hippocamp

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

Aetherspouts

For each attacking creature, its owner puts it on their choice of the top or bottom of their library.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Time Stretch

Target player takes two extra turns after this one.

Mystic Confluence

Choose three. You may choose the same mode more than once.
• Counter target spell unless its controller pays {3}.
• Return target creature to its owner's hand.
• Draw a card.

Ghostly Flicker

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

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Snap

Return target creature to its owner's hand. Untap up to two lands.

Blur

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

Mystic Sanctuary

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

Aetherize

Return all attacking creatures to their owner's hand.

Fierce Guardianship

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

Archmage of Runes

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, draw a card.

Case of the Ransacked Lab

Instant and sorcery spells you cast cost {1} less to cast.
To solve — You've cast four or more instant and sorcery spells this turn. (If unsolved, solve at the beginning of your end step.)
Solved — Whenever you cast an instant or sorcery spell, draw a card.

Sea Gate, Reborn

Sea Gate Restoration

Draw cards equal to the number of cards in your hand plus one. You have no maximum hand size for the rest of the game.

Sea Gate Restoration // Sea Gate, Reborn

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Capsize

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Return target permanent to its owner's hand.

Sublime Epiphany

Choose one or more —
• Counter target spell.
• Counter target activated or triggered ability.
• Return target nonland permanent to its owner's hand.
• Create a token that's a copy of target creature you control.
• Target player draws a card.

Finale of Revelation

Draw X cards. If X is 10 or more, instead shuffle your graveyard into your library, draw X cards, untap up to five lands, and you have no maximum hand size for the rest of the game.
Exile Finale of Revelation.

Sol Ring

Reliquary Tower

Pongify

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

Frantic Search

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

Wizard Class

(Gain the next level as a sorcery to add its ability.)
You have no maximum hand size.
{2}{U}: Level 2
When this Class becomes level 2, draw two cards.
{4}{U}: Level 3
Whenever you draw a card, put a +1/+1 counter on target creature you control.

Fellwar Stone

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

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.

Terrain Generator

{T}: Add {C}.
{2}, {T}: You may put a basic land card from your hand onto the battlefield tapped.

Castle Vantress

This land enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

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.