Blue Elemental Blast

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

Tidal Visionary

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

Coast Watcher

Wrath of Marit Lage

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

Shifting Sky

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

Hydroblast

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

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.

Distorting Lens

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

Douse

Vodalian Mystic

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

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."

Sway of Illusion

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

Archaeomancer

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

Flash Flood

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

Weatherseed Faeries

Scuttlemutt

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

Wash Out

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

Prismwake Merrow

Flash
When Prismwake Merrow enters the battlefield, target permanent becomes the color or colors 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.

Prismatic Lace

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

Hibernation

Return all green permanents to their owners' hands.

Sea Sprite

Crypsis

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

Well-Laid Plans

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