In the 'What If?' issue, when the Annihilation Wave is headed towards the moon and then decides to sacrifice his life by staying behind to fight them while Reed and the Inhumans head back to Earth. Then Cap and Iron Man, previously seen beating each other to a pulp, settle their differences and stay with Nova. Presumably the three of them die and not only manage to save the Earth, but they also stop the Annihilation Wave altogether and save the universe. Bad. Ass.
Richard Rider manage to successfully fight off the Phalanx infection, then fight his way out of the heart of the Babel Spire, even with most of his power having to keep the infection in check.
Moondragon turning into a dragon, with Phyla riding her.
Though it becomes much less awesome when she reveals she's being slowly possessed by the Dragon of the Moon.
Nova, Gamora, Drax and Warlock performing a Big Damn Heroes, saving Peter Quill from Ultron.
After going through hell to find 'The Savior', including losing the love her life, Quasar finally manages to bring him to the final battle with Ultron ... only to deliver the killing blow herself.