Yeah, I was thinking maybe the group of slaves could bust out of the jail and join the rebellion against the wizards.  The wizards magic is kind of interesting, they pull energy out of other things and convert it into magic power.  If one was standing by a fire, and wanted to burn a tree, they could take the energy of the fire and from there expel the energy from their body and burn the tree.  The leader is just a random guy who decided that the wizards were being unfair and decided to fight them, but he's extra powerful because he learned how to steal the lives of wizards.  Like with the wizard and the fire, only this guy and pull the energy out of humans as well as plants, lightning, etc.  If you want to join your character can have magic of a kind, either forging, where you can create temporary objects out of other substances.  Like a sword of fire, however that would use a lot of energy.  Or converting, where you take the energy and convert it into some other type of energy and then eject it at something else.  Or witchcraft, where you mostly deal with potions and healing herbs.  Things like that, or you can just be a warrior, and fight magic with physical attacks.