Boreal Griffin

Below the flying keyword sits a toggle that does nothing until the manabase earns it: this body's first strike wakes only when a snow source supplies the activation mana, gating a combat-relevant upgrade behind a deckbuilding commitment rather than handing it out free. White fliers have always traded poorly in the air against equal or larger bodies; pay the snow mana before blockers and the math flips, letting a 3/2 hold against a bigger attacker and live. The shape of the ability matters as much as the cost. First strike doesn't stack, so a single activation per turn is all any line ever wants, which makes the upgrade a one-time switch rather than a mana sink and keeps it cheap to fund once the snow sources are online. That leaves two readings depending on whether you've paid the construction tax the snow symbol asks of everything carrying it: a forgettable five-mana flier to anyone running ordinary lands, a repeatable defensive threat to anyone who has narrowed the manabase to feed it. The bargain (a sleeping upgrade in exchange for a snow-heavy deck) is exactly the trade the supertype was built to sell, and few cards demonstrate it more plainly. The activation asks only that the mana come from a snow source (colored or colorless, the symbol is agnostic on that point), so the worse your snow density, the worse the card.