Frost Trickster

Man-o'-War taught blue that a body plus a tempo swing on entry is the shape that keeps a bounce-adjacent creature honest, and this is that lesson rebuilt around a tap-down instead of a bounce. Where the classic bounce buys a full turn but hands the card back, freezing a creature strands a blocker or attacker without returning it to hand: you get the aggression clock, but you don't reset their card advantage or refund their sunk mana. The flying gives the effect a second dimension, because the pressure you apply in the air isn't the same pressure you're spending the enters trigger to buy on the ground; the modest 2/2 does more work than its numbers imply once the opponent's best ground defender is turned sideways. Two constraints keep the design from spiraling. The tap is restricted to an opposing creature, which forecloses the self-untap loops that make other tap effects into engines, and it fires only on entry, so there's no repeatable lock, just a single well-timed removal of a defender: tapped now, and held down through the next untap step it would otherwise get. It reads as filler right up until you're the one facing a flyer with your best blocker frozen and your untap step already spent for nothing.