Once your characters level enough, let them loose on enemy units. Laugh as they are destroyed one by one by one.
An example of the above and also a different awesome - when a character completely owns a villain who talks smack on them. My last time was Pelleas and Lekain, so I'll use that as an example here. So Pelleas went up against Lekain. Lekain taunted him, told him how worthless he was, etcetera. Pelleas countered with the Power of Friendship. Then he attacked, used Disarm and thus completely ruined Lekain's ability to counter-attack. Then he used Adept, and then he used Flare. Lekain died horribly without even coming close to touching Pelleas. I'm sure you've all had your times when that's happened.
The end of Part 2, involving The Greil Mercenaries' Big Damn Heroes moment to rescue Lucia from execution.
Kurthnaga's Big Damn Heroes moment at the end of 3-13, levelling a castle with a single attack to provoke a ceasefire.
Vantage combined with Wrath. Basically, if a character has both of these skills and ends up in a really bad situation, they go Super Saiyan. This troper first encountered this combination when he accidentally overextended Nephenee on his first playthrough of Path of Radiance. This was just before Nephenee Took a Level in Badass, so she was still fairly fragile, particularly to magic users, and got reduced to 3HP from a Meteor. This troper sadly resigned himself to restarting the chapter, as four cavalier and a paladin were within attacking range...only to watch Nephenee continually activate both Vantage and Wrath, wiping out the horsemen en masse, dodging the second Meteor strike, and surviving long enough for Rhys to get to her.