There are two battles where you must use an item, and those occasions will not end in being disqualified: the Hammer of Righteousness in the "Catacombs" and Molten Metal in "Black Iron Furnace". However, do not use items in any other battle. This will not prove difficult if you have a decent character and use abilities for most of your healing and damage. Use the Assassin instead of the Paladin because of the "strike" abilities. Also, select the easy difficulty setting. The most difficult battle will be shortly after the start, against a troll that is attacking Verloren. You cannot use the torch to stop it from regenerating.