The Horned King's entrance via Villain Teleportation. Shame he never demonstrates any more (non-Cauldron) magic afterward.
Fflewddur, though less competent than his book counterpart, gets a beautiful one when he ruins the witches' Batman Gambit by turning their own words against them: "We never give anything away! We bargain — we trade, remember?"
Followed by the "Oh, pull yourself together, Madam!" to Orwen.
Eilonwy helping Taran escape the castle.
Eilonwy demanding Taran's respect. Once she gets it, she respects him as well.
Taran admitting he's not a hero is pretty awesome, since he'd been dreaming of being one for most of the movie. It takes a lot of courage to admit you're not cut out for something.
Creeper wearing the Horned King's headdress and laughing maniacally as he escapes.
The rise of the Cauldron Born is one for the animators. It is terrifying.
Gurgi's sacrifice to stop the Cauldron.
The Horned King trying to sacrifice Taran to the Cauldron to regain his army, even grabbing at him when he was safe and shoving him towards its suction.