Fleetfeather Cockatrice

Flash is what turns this from a fine flyer into a genuine combat lever. A 3/3 with flying and deathtouch that can arrive on the opponent's attack step rewrites the math of any race: the deathtouch means it trades up against anything that swings into the air or gets blocked by it, and the flash means the opponent commits first and finds the answer already waiting. The monstrosity ability is the late-game patch for a body that would otherwise stop mattering once the board grows past it; sinking seven mana into three +1/+1 counters converts a flooded hand into a 6/6 flying deathtoucher that ends games on its own. Deathtouch is the load-bearing keyword, because it makes both halves of the card asymmetric: a 6/6 deathtouch flyer is functionally unblockable by anything that values its blockers, and a flash-held 3/3 deathtouch flyer punishes overextension. It is a mana-sink design dressed as a flash threat, built to be a serviceable body when you first deploy it and a finisher several turns later once the rest of your hand has run dry.