I broke it. Wizard ability, combined with high energy replenish, gold find, and damage, to buy gems. I started getting 2 billion gold per cast of fireball. I went from fighting level 40 monsters to fighting level 1500 monsters in about 15 minutes. I could fight level 3500+ monsters but most of them give me negative money.
New version just went live. It has MUCH better balance. Hope you'll check it out!