Balance Wizards get the Judgement (my favorite spell, lol) at Level 28. It is a quest from Alhazred (spelling error?), the balance professor at the Krokosphinx. I believe you must defeat 2 bosses at once in a warehouse in Marleybone. I hope this helped! :-D
Judgement IS nice, but as you progress, you'll use it less and less. With good gear and blades, you can get 1200+ from a spectral blast for only 2 power pips and 2500+ from a hydra for only 3 power pips. Judgement is a good finisher, but master the spectral blast and hydra, and you'll be able to tear up anything that gets in your way!
By the way, when you get to celestia and get enchantment treasure cards as part of your regular deck, at 4 pips, sandstorm becomes the "hit all" spell of choice over power nova. More damage for 1/2 the pips because the power nova is classed as a charm and can't be enchanted.