How to break the game: Only obtain abilities, upgrade nothing but Power Attack, upgrade that to max, boom. By the final boss every base stat will be maxed out, as well as power attack, easily the best ability in the game due to the fact it destroys bosses.
Always get Cure and Barrier, no matter what your faction or play style is. Cure = +50% health for 5 MANA! Barrier gives you a permanent 30% damage reduction for the rest of the fight. Use barrier at the start of every boss fight and use cure when hurt, and the game becomes much, much easier.
Don't spend any points any anything besides attributes and the power attack skills, and you can max out all attributes, as well as the power attack, easily the best way to deal with bosses in the entire game.