Which wizard casts the biggest spell?

Gandalf the Grey - The Lord of the Rings (2001)

Ulrich of Craggenmoor -- Dragonslayer (1981)

Merlin -- Excalibur (1981)

Akiro -- Conan the Barbarian (1982)

Albus Percival Wulfric Brian Dumbledore -- Harry Potter (2001-2011)

Mickey Mouse -- "The Sorcerer's Apprentice," Fantasia (1940)

The Wizard of Oz -- The Wizard of Oz (1939)

Robert Angier -- The Prestige (2006)