Which school of magic do you prefer and why?

Since I usually play as a warrior rather than a mage (and my spells are mostly buffs and debuffs) and often choose the Swamp faction, I take Earth and Wisdom skills (the latter only if there's a second castle where I can find something interesting like an explosion spell or a city portal). My three favorite magic schools are Slow, Chain Lightning, and Shield. Of course, Haste is also important, but Air magic isn't for me.