One for the agent in Chapter 3, Mission 5. Nick Fury himself has this to say:
''I have to tell you, Agent. You get shot down in Doom's back yard, and come out with Vulture and Sandman as trophies. Let me step out of my formal Director's role long enough to say: That was flat-out badass."
The increasing number of niche and obscure characters (although some of the Fan Dumb still waiting for 'Iceman, Silver Surfer etc.' might disagree) playable. This game is seriously rivalling Super Hero Squad Online in its roster size and variety. It features the following characters in their first playable appearance in any video game: Ares, Black Bolt, Captain Britain, Constrictor, Daimon Hellstrom, Fantomex, Hercules, Magik, Mockingbird, Omega Sentinel, Rescue, Satana, Shatterstar, Sif, Thane, Thundra and Union Jack. It also includes many other heroes with a few playable instances.
Heck, as part of the Infinity Spec Ops tying into the Marvel miniseries of the same name, Thane actually made his official named debut in M:AA.
Any time you do a Three Bird on Chapter 12. The missions - aside from the Premium one - consist of nothing but mini bosses and bosses. No deploy, no threats, just villains for you to duke it out.
Bonus badass points if you manage to get "Perfection" when doing this. Even more badass points if you accomplish it on Challenge Mode (a mode where enemies are five levels above you).
Consider all the work the Avengers have done since the Pulse. They stopped Loki from turning New York to stone, quelled at least 3 different Mutant riots, stopped Mystique from turning Manhattan into a mutant island, saved the UN from evil knockoff Avengers, rescued more than one of their own from evil, and of course, fought off scores of villains.
Given the difficulty of Blackheart, the latest Spec Ops Group Boss, just figuring out a way to survive his onslaught while dealing considerable damage is quite a feat. Even moreso if you manage to destroy him during your fight.
Yes, while it might be just gameplay, it's still awesome that Ares can afflict Thanos of all people with 'Broken Will'.
A meta one for Deadpool that may also be CMOF, he is the best choice Scrapper for dealing with Thanos in most of his forms (save Bruiser for obvious reasons) and even more so since his recent buff, considering their shared romantic history with Death makes it even better.
An Offscreen Moment of Awesome for Captain Britain in the Thor 2 SO where he is implied to have fought off Kurse, the then group boss, on his own