Riverfall Mimic

Whenever you cast a spell that's both blue and red, this creature has base power and toughness 3/3 until end of turn and can't be blocked this turn.

Volatile Fjord

({T}: Add {U} or {R}.)
This land enters tapped.

Flame Jab

Flame Jab deals 1 damage to any target.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Oona's Grace

Target player draws a card.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Island

High Tide

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

Burn Trail

Burn Trail deals 3 damage to any target.
Conspire (As you cast this spell, you may tap two untapped creatures you control that share a color with it. When you do, copy it and you may choose a new target for the copy.)

Merrow Levitator

{T}: Target creature gains flying until end of turn.
Whenever you cast a blue spell, you may untap this creature.

Crag Puca

{U/R}: Switch this creature's power and toughness until end of turn.

Hatchet Bully

{2}{R}, {T}, Put a -1/-1 counter on a creature you control: This creature deals 2 damage to any target.

Claws of Gix

{1}, Sacrifice a permanent: You gain 1 life.

Stream Hopper

{U/R}: This creature gains flying until end of turn.

Outrage Shaman

Chroma — When this creature enters, it deals damage to target creature equal to the number of red mana symbols in the mana costs of permanents you control.

Inside Out

Switch target creature's power and toughness until end of turn.
Draw a card.

Unwilling Recruit

Gain control of target creature until end of turn. Untap that creature. It gets +X/+0 and gains haste until end of turn.

Noggle Bandit

This creature can't be blocked except by creatures with defender.

Mindwrack Liege

Other blue creatures you control get +1/+1.
Other red creatures you control get +1/+1.
{U/R}{U/R}{U/R}{U/R}: You may put a blue or red creature card from your hand onto the battlefield.

Noggle Bridgebreaker

When this creature enters, return a land you control to its owner's hand.

Dominus of Fealty

Flying
At the beginning of your upkeep, you may gain control of target permanent until end of turn. If you do, untap it and it gains haste until end of turn.

Clout of the Dominus

Enchant creature
As long as enchanted creature is blue, it gets +1/+1 and has shroud. (It can't be the target of spells or abilities.)
As long as enchanted creature is red, it gets +1/+1 and has haste.

Noggle Hedge-Mage

When this creature enters, if you control two or more Islands, you may tap two target permanents.
When this creature enters, if you control two or more Mountains, you may have this creature deal 2 damage to target player or planeswalker.

Spell Syphon

Counter target spell unless its controller pays {1} for each blue permanent you control.

Jaws of Stone

Jaws of Stone deals X damage divided as you choose among any number of targets, where X is the number of Mountains you control as you cast this spell.

Nucklavee

When this creature enters, you may return target red sorcery card from your graveyard to your hand.
When this creature enters, you may return target blue instant card from your graveyard to your hand.

Mountain

Shrewd Hatchling

This creature enters with four -1/-1 counters on it.
{U/R}: Target creature can't block this creature this turn.
Whenever you cast a blue spell, remove a -1/-1 counter from this creature.
Whenever you cast a red spell, remove a -1/-1 counter from this creature.