Glen Elendra Guardian

The clever inversion is that the very thing dragging the body down is what powers its answer: a -1/-1 counter that makes this a 2/3 on arrival, held in reserve as ammunition. Feed it to the permission ability and two things happen at once. You counter a noncreature spell, and stripping the counter restores the flier to its full 3/4 printed size just as the ability goes dead. That is the rhythm: one charge, spent once, and the payoff for spending it is a bigger threat that keeps swinging. So the choice is pointed rather than repeatable. You get a single clean answer, and using it converts a diminished creature into a full-size beater. The consolation cantrip (the countered spell's controller draws) keeps the denial fair, softening the tempo hit and turning a hard counter into a taxed one. Flash makes it treacherous to play around: hold the mana up as a bluff, ambush at instant speed, or drop a flying blocker on a turn when no counter is needed. It sits in the lineage of blue creatures that fold soft permission into a warm body, the Venser and Snapcaster Mage instinct of stapling a spell to a threat, but the counter-as-fuel framing gives it a distinct arc, where protecting yourself and completing your own creature's growth are the same act.