Plumecreed Escort

The protection is priced into the ambush. Flash and flying already make this a serviceable end-of-turn play that trades up or blocks something coming over the top, but the enters trigger changes what the flash window is buying: hold it until an opponent points removal at your best creature, then flash it in and hand that creature hexproof until end of turn. The spot removal fizzles, and you keep a 2/1 flyer for the trouble. It is a counterspell shaped like a body, and the two halves reinforce each other rather than sitting side by side; the flash is what lets the hexproof arrive exactly when it matters, since a sorcery-speed version of this could never react to a spell already on the stack. The catch that keeps it fair is narrower than the hexproof suggests. The Escort cannot shield itself from removal aimed at it in response to its own trigger: that removal resolves first, killing the Escort before the trigger ever grants hexproof, so the ability targets nothing and does nothing. And the protection only touches a single creature and only through end of turn, so it is useless against board wipes or edicts that never point at a specific creature. That confines it to a defensive reflex against targeted spells, which is precisely the interaction this kind of small blue flash flyer has always been built to punish.