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.