Within Mutants and Masterminds, if you have a feat called Acrobatic Bluff (Agile Feint in 3E), you can use an Acrobatics check in place of Bluff (Deceive in 3E) for the purpose of feinting to make someone flat-footed for your next attack. It is, by default, a Standard action, but the game allows you to do it as a Move action with a -5 penalty (which in 2E can be countered by a 1 PP Challenge Feat to remove that penalty). Obviously, making it a Free action for a -10 penalty can cause issues with the action economy since it's essentially cost-free (other than possibly racking up the -1 penalties to subsequent attempts against the opponent in 2E), but one of the iconic moves in the comic books is the agile gymnast doing a series of handsprings and cartwheels across the floor to confuse the opponent before striking (c.f. Harley Quinn in many of her performances).
How would allowing an Acrobatic Bluff check at a -10 penalty for doing it as part of movement break the system? Obviously, someone with a high enough bonus might be able to consistently overcome the penalty (particularly if the GM lets them buy off the penalties with Challenge Feats) and there's some risk of people doing it all of the time "just because", but it seems largely reasonable to me. Am I missing anything other than that it isn't in the book already?
I posed the same question on the Atomic Think Tank and the point was raised that the Charge action is a Standard action where you can move 30 feet and attack. Doing the Acrobatic Bluff as a Move action at the beginning and then doing a Charge is a viable action here, it seems. It feels really strange to me since mechanically it works out as "let me distract you by doing a backflip and then run straight at you and attack!" but it does achieve a similar effect and only with slight modifications to attack and defense bonuses (in 2E, +2 to attack and -2 to defense. In 3E, -2 to attack).