Excalibur Scooby/Scooby's Luck of the Irish/Scooby's Escape from Atlantis

Plot:

Merlin the Magician proclaims Scrappy King of England when Scrappy pulls a magical sword from a rock. / Shaggy, Scooby, and Scrappy contend with a mischievous leprechaun and a menacing banshee. / The threesome battle sea creatures and an evil Centaur.