Subjugator Angel

A Falter effect wearing a creature costume. The mass tap on entry is the entire sale: every blocker your opponents control goes horizontal the moment the angel resolves, and a defending side with no untapped creatures is a defending side you swing into unopposed. Because there is no flash, the angel lands in your main phase, which is exactly where you want it: develop it before combat, then attack with the board you already committed into open air. The angel sits out that first strike itself, summoning-sick and watching, so its 4/3 flying body only starts mattering on later turns. That timing is the whole discipline of the design. The tap is a one-shot entry trigger, not a recurring lock, so it purchases a single uncontested attack step from your existing attackers, after which the opposition untaps and resumes normal service. It rewards a board that can end the game on the turn the angel arrives rather than a defensive panic button; the creatures already in play do the killing, the angel just clears the runway. The lineage of finishers that double as tempo swings runs long, but attaching the "everything is tapped, now attack" promise to an evasive body that survives to close on subsequent turns is a narrower slice of it, and this fills that slice cleanly.