Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

Cerulean Wisps

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

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Sisay's Ingenuity

Enchant creature
When this Aura enters, draw a card.
Enchanted creature has "{2}{U}: Target creature becomes the color of your choice until end of turn."

Sway of Illusion

Any number of target creatures become the color of your choice until end of turn.
Draw a card.

Llawan, Cephalid Empress

When Llawan enters, return all blue creatures your opponents control to their owners' hands.
Your opponents can't cast blue creature spells.

Shadow Puppeteers

Flying, ward {2}
When this creature enters, create two 1/1 black Faerie Rogue creature tokens with flying.
Whenever a creature you control with flying attacks, you may have it become a red Dragon with base power and toughness 4/4 in addition to its other colors and types until end of turn.

Tidal Visionary

{T}: Target creature becomes the color of your choice until end of turn.

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.

Distorting Lens

{T}: Target permanent becomes the color of your choice until end of turn.

Chill

Rainbow Crow

Flying
{1}: This creature becomes the color of your choice until end of turn.

Cowardice

Whenever a creature becomes the target of a spell or ability, return that creature to its owner's hand. (It won't be affected by the spell or ability.)

Neurok Transmuter

{U}: Target creature becomes an artifact in addition to its other types until end of turn.
{U}: Until end of turn, target artifact creature becomes blue and isn't an artifact.

Spectral Shift

Choose one —
• Change the text of target spell or permanent by replacing all instances of one basic land type with another. (This effect lasts indefinitely.)
• Change the text of target spell or permanent by replacing all instances of one color word with another. (This effect lasts indefinitely.)
Entwine {2} (Choose both if you pay the entwine cost.)

Whim of Volrath

Buyback {2} (You may pay an additional {2} as you cast this spell. If you do, put this card into your hand as it resolves.)
Change the text of target permanent by replacing all instances of one color word with another or one basic land type with another until end of turn. (For example, you may change "nonred creature" to "nongreen creature" or "plainswalk" to "swampwalk.")

Blind Seer

{1}{U}: Target spell or permanent becomes the color of your choice until end of turn.

Leveler

When this creature enters, exile all cards from your library.

Shifting Sky

As this enchantment enters, choose a color.
All nonland permanents are the chosen color.

Mercurial Transformation

Until end of turn, target nonland permanent loses all abilities and becomes your choice of a blue Frog creature with base power and toughness 1/1 or a blue Octopus creature with base power and toughness 4/4.

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.

Kormus Bell

All Swamps are 1/1 black creatures that are still lands.

Clara Oswald

Impossible Girl — If Clara Oswald is your commander, choose a color before the game begins. Clara Oswald is the chosen color.
If a triggered ability of a Doctor you control triggers, that ability triggers an additional time.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Douse

Crystal Shard

{3}, {T} or {U}, {T}: Return target creature to its owner's hand unless its controller pays {1}.

Metamorphic Blast

Spree (Choose one or more additional costs.)
+ {1} — Until end of turn, target creature becomes a white Rabbit with base power and toughness 0/1.
+ {3} — Target player draws two cards.

Wash Out

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

Jaded Response

Counter target spell if it shares a color with a creature you control.

Sleight of Mind

Change the text of target spell or permanent by replacing all instances of one color word with another. (For example, you may change "target black spell" to "target blue spell." This effect lasts indefinitely.)

Aboshan, Cephalid Emperor

Tap an untapped Octopus you control: Tap target permanent.
{U}{U}{U}: Tap all creatures without flying.

Sea Kings' Blessing

One or more target creatures become blue until end of turn.

Hibernation

Return all green permanents to their owners' hands.

Alter Reality

Change the text of target spell or permanent by replacing all instances of one color word with another. (This effect lasts indefinitely.)
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Quickchange

Target creature becomes the color or colors of your choice until end of turn.
Draw a card.

Prismwake Merrow

Flash
When this creature enters, target permanent becomes the color or colors of your choice until end of turn.

Prismatic Lace

Target permanent becomes the color or colors of your choice. (This effect lasts indefinitely.)

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

Scuttlemutt

{T}: Add one mana of any color.
{T}: Target creature becomes the color or colors of your choice until end of turn.

Winter Moon

Players can't untap more than one nonbasic land during their untap steps.

Flow of Knowledge

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

Insight

Whenever an opponent casts a green spell, you draw a card.

Aetherize

Return all attacking creatures to their owner's hand.

Master of Waves

Protection from red
Elemental creatures you control get +1/+1.
When this creature enters, create a number of 1/0 blue Elemental creature tokens equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Engulf the Shore

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

Moonlace

Target spell or permanent becomes colorless.

Vodalian Mystic

{T}: Target instant or sorcery spell becomes the color of your choice.

Govern the Guildless

Gain control of target monocolored creature.
Forecast — {1}{U}, Reveal this card from your hand: Target creature becomes the color or colors of your choice until end of turn. (Activate only during your upkeep and only once each turn.)

Mind Bend

Change the text of target permanent by replacing all instances of one color word with another or one basic land type with another. (For example, you may change "nonblack creature" to "nongreen creature" or "forestwalk" to "islandwalk." This effect lasts indefinitely.)

Kefnet's Monument

Blue creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature an opponent controls doesn't untap during its controller's next untap step.

Thoughtlace

Target spell or permanent becomes blue. (Mana symbols on that permanent remain unchanged.)

Swirl the Mists

As this enchantment enters, choose a color word.
All instances of color words in the text of spells and permanents are changed to the chosen color word.

Transit Mage

When this creature enters, you may search your library for an artifact card with mana value 4 or 5, reveal it, put it into your hand, then shuffle.

Trait Doctoring

Change the text of target permanent by replacing all instances of one color word with another or one basic land type with another until end of turn.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

Island

Fylamarid

Flying
This creature can't be blocked by blue creatures.
{U}: Target creature becomes blue until end of turn.

Archmage Emeritus

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

Unwind

Counter target noncreature spell. Untap up to three lands.

Indigo Faerie

Flying
{U}: Target permanent becomes blue in addition to its other colors until end of turn.

Defiler of Dreams

Flying
As an additional cost to cast blue permanent spells, you may pay 2 life. Those spells cost {U} less to cast if you paid life this way. This effect reduces only the amount of blue mana you pay.
Whenever you cast a blue permanent spell, draw a card.

Rewind

Counter target spell. Untap up to four lands.

Flash Flood

Choose one —
• Destroy target red permanent.
• Return target Mountain to its owner's hand.