Everytime Yuuri suddenly turns into the "Maoh" you know some seriously awesome magical water works are about to school the bad guys.
Wolfram is apparantly so awesomely pretty, his face revives the sick and dying in a hospital unintentionally.
Gunter and Conrads fight during the Big Shimaron Arc.
Yuuri's mother fighting off otherworldly enemies. With a broom.
Conrad and Aldelberts showdown.
In the second OVA episode, all the tournament participants team up to take down a group of thugs. Awesomeness was had.
Geigenhuber slicing a few catapults in half.
Conrad and Yozaks miasma induced duel on the snow mountain is pretty awesome to watch.
Yuuri and Shori's magic fight.
Shinou/The Great One, was a pretty epic guy. What with saving the world with his army and all.
Then of course getting possessed by the evil he was fighting and coming up with a plan with the help of his buddy, the great sage, that involves destroying his own soul in order to permanantly eradicate said evil from the world. Takes guts to go through with that.