The Sophie versus Richard scene in Lhant where the duo go head to head and end it with the former slamming the latter into a cliff after a dueling with masses of light and darkness. Also Asbel's Big Damn Heroes moment when he saves Sophie when Richard has her cornered.
Perhaps not on the scale as the above, but near the end of Lineage and Legacies, Asbel prepares to let Lambda temporarily take over his body to shut down Fodra's core. The crowning moment is for Hubert, though:
Hubert: Hear me well, Lambda. If you refuse to release my brother, I will not be held responsible for the consequences.