Hydroblast

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

Prismatic Strands

Prevent all damage that sources of the color of your choice would deal this turn.
Flashback—Tap an untapped white creature you control. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tireless Tribe

Discard a card: This creature gets +0/+4 until end of turn.

Stonehorn Dignitary

When this creature enters, target opponent skips their next combat phase.

Mystic Crusader

Protection from black and from red
Threshold — As long as seven or more cards are in your graveyard, this creature gets +1/+1 and has flying.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Mystic Visionary

Threshold — This creature has flying as long as seven or more cards are in your graveyard.

Valor

First strike
As long as this card is in your graveyard and you control a Plains, creatures you control have first strike.

Mystic Zealot

Threshold — As long as seven or more cards are in your graveyard, this creature gets +1/+1 and has flying.

Shadow Rift

Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)
Draw a card.

Circular Logic

Counter target spell unless its controller pays {1} for each card in your graveyard.
Madness {U} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Mystic Penitent

Vigilance
Threshold — As long as seven or more cards are in your graveyard, this creature gets +1/+1 and has flying.

Snow-Covered Plains

Citadel Gate

This land enters tapped.
As this land enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Resilient Wanderer

First strike
Discard a card: This creature gains protection from the color of your choice until end of turn.

Standard Bearer

While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least one Flagbearer on the battlefield if able.

Snow-Covered Island

Late to Dinner

Return target creature card from your graveyard to the battlefield. Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Inside Out

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

Basilisk Gate

{T}: Add {C}.
{2}, {T}: Target creature gets +X/+X until end of turn, where X is the number of Gates you control. Activate only as a sorcery.

Sea Gate

This land enters tapped.
As this land enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.