I'd go for Locust. Try targeting me now damn police! HAA!!!
You do understand that you only have 3 spells in it... Battle Roar, Entangling roots and something else if i recall correctly...
Spell Steal, how bout that?
Okay then I'll take "Pillage", punch about hundred times the most expansive building in the world, makes billions of money, buy Warcraft 3 from Blizzard, code an ultimate and unique spellbook, which contains all spells and use this one =)
How about Spell Steal?
Isn't it sort of rule them all?