Aven Sunstriker

The combat math is the whole point, and double strike is what bends it: every +1/+1 counter the megamorph delivers is worth two extra points across the swing rather than one. Cast face down, the threat reads like any other 2/2 lurking under a morph, and the flip can be made after blocks have been declared, so the counter, the flying, and the double strike all reveal themselves once the defender has committed. Turned face up, the base 1/1 grows to 2/2 with double strike and now flies, which is four damage in the air instead of the two an unblocked morph promised. An opponent who waves the attacker through expecting two takes four; one who blocks with something small watches the trade dissolve when it grows mid-combat and strikes first. The fragility on the face-up body (a 2/2 even with the counter) is what the megamorph cost is buying around: you are not paying for a durable threat, you are paying to misrepresent the size of an attack until the defender has already chosen how to block. That sequencing is the design. The card sandbags its real shape, holds open the flying double-strike threat as a bluff, and cashes the megamorph cost after blockers are locked in. The window closes on the blocker's assignment, not on the ability to respond: the defender can still act once it flips, but by then the two-for-four swing is already sized.