1) Mirror of Ice. Who wouldent want a spell that could double as a way to inspect your awsome visage -and- make your foes cry?
2) Burning Speed. Funniest_Skill_Ever. Set your self on fire and run around a while till you preform a flaming tackle.
3) Shockwave. Cool picture, cool effect, and gives me dellusions of grandur involving sending stupid warriors flying 100 meters. yummy.
(now in all seriousness, my fave 3 for practicality are: Fireball, Water Trident and Whirlwind.)