Hee hee. The most broken build I have done in my handful of playings is my cantrip build. I gave the item that gave growth +1 to the left side to my sorcerer. My dancer had the item that gave poison to the top and bottom and an item that improved the middle. As soon as my sorcerer hit the reroll cantrip a few times, it kept growing and eventually I was able to get about 20 rerolls. All the time my dancer was getting either 2 damage cantrips or 1 damage poison cantrips each reroll. In addition I was able to get a ton of mana since the middle cantrip for my sorcerer had growth as well and kept growing each time I landed on it. Lots of fun and an easy win on hard. :)
I replayed in easy mode with the 2 extra rerolls and was able to duplicate this with sorcerer and dragon egg combo fairly easily. Once the reroll train get started, it basically became an infinite cycle as landing on the reroll side increases the reroll by 1 each time and increases the number of rerolls available. I got up to about 400 rerolls and 475 mana before I got bored and ended it. I killed Hexia with about 30 poison stacks using repeated miasma spells.