I wonder why my previous comment about wizard has got rated as bad?
Wizard is really the easiest choice, just be careful in the beginning and don't afraid to use scroll of summoning. Focus just on intelligence and speed, the rest does not really matter. Polymorph is very important to kill tanks: use it + fireball. Glide and blink saved my ass couple of times. Perks: fireball to the max and inspiration, then the rest. Frost blast is really good, but without blink or teleport is risky, 'cause you harm yourself when attack a closed enemy.
With this strategy you can clear all the acts on hard mode easily and go to around 40th tower level to get the impossible badge even without sophisticated time management. Worked for me and friend of mine.
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