Archaeomancer

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

Vodalian Mystic

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

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.

Wrath of Marit Lage

When Wrath of Marit Lage enters, tap all red creatures.
Red creatures don't untap during their controllers' untap steps.

Blind Seer

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

Hibernation

Return all green permanents to their owners' hands.

Snap

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

Scuttlemutt

{T}: Add one mana of any color.
{T}: Target creature becomes the color or colors 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.

Flash Flood

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

Distorting Lens

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

Hydroblast

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

Crypsis

Target creature you control gains protection from creatures your opponents control until end of turn. Untap it.

Prismwake Merrow

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

Sea Sprite

Essence Leak

Enchant permanent
As long as enchanted permanent is red or green, it has "At the beginning of your upkeep, sacrifice this permanent unless you pay its mana cost."

Weatherseed Faeries

Wash Out

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

Douse

Well-Laid Plans

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

Tidal Visionary

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

Cerulean Drake

Flying
Protection from red (This creature can't be blocked, targeted, dealt damage, enchanted, or equipped by anything red.)
Sacrifice Cerulean Drake: Counter target spell that targets you.

Coast Watcher

Prismatic Lace

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