Glamerdye

Change the text of target spell or permanent by replacing all instances of one color word with another.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Vodalian Mystic

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

Llawan, Cephalid Empress

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

Tidal Visionary

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

Blind Seer

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

Well-Laid Plans

Prevent all damage that would be dealt to a creature by another creature if they share a color.

King Crab

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

Heartstone

Activated abilities of creatures cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Distorting Lens

{T}: Target permanent 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.

Insight

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

Douse

Dismiss into Dream

Each creature your opponents control is an Illusion in addition to its other types and has "When this creature becomes the target of a spell or ability, sacrifice it."

Hydroblast

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

Flash Flood

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

Willbreaker

Whenever a creature an opponent controls becomes the target of a spell or ability you control, gain control of that creature for as long as you control Willbreaker.

Scuttlemutt

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

Hibernation

Return all green permanents to their owners' hands.

Wash Out

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

Blue Elemental Blast

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

Shifting Sky

As Shifting Sky enters, choose a color.
All nonland permanents are the chosen color.