Just got a cool idea for Brutalities, that could fit with the audio tease. What if...
First, you input a short button sequence just like a fatality (maybe with a special condition during the match like Babalities, maybe not), this intiates "Brutality Mode" which darkens the background, has your character get closer to his opponent and changes the camera angle.
Then, the timing becomes really strict and you have to input the full 11-button combination to get the full brutality, an enraged beatdown (personalised for every character (ex:Scorp uses spear and fire)) with an incredibly gory finishing hit.
If at any point in your button combination you input the wrong command, the Brutality will end at the number of hits you got right with a violent finisher, but one that's much less "final" than the complete one.
That way, pretty much anybody can "input" a Brutality, but only the best players can get the full finisher. I would personally be for implementing a special condition like, for example, bringing back Mercy from UMK3 (even though they weren't tied to Brutalities before).
Imagine, you beat your opponent in a great 3 round match. Then you give him more health. You beat him again. You completely destroy his face with a full brutality. Wouldn't that be incredibly rewarding?