Okay, I've figured out how to win this game at level 1. Bring 10 healing potions before each boss battle, hit them with the Poison spell first turn (which deals 10% of their max health and doesn’t expire), then drink the potions every turn to recover from the damage (sometimes guard if I'm still above half health). When the boss's health stops ticking down, deliver the final hit.
Not like it’s easy of course, the fire and lightning bosses are real bastards, and I can only use my freeze Bimbo spell once or else I’ll reach level 2.
The final boss is immune to poison, but since Bimbo spells can be used here without filling the Bimbo meter burn damage works in much the same way.
The ending is that I got free of the curse, return to the tavern, and have a gay crush on the blacksmith. Awesome