Conquest of the Time Master — R.L. Stine

The king's daughter has disappeared into the caverns of time. Now you must journey through time -- to the past and the future to rescue her from the awesome power of the Time Master. You must choose now: will you be the wizard or the warrior? As the Wizard, you will take with you the Book of Spells. You will be master of all its mysterious magic. As the Warrior, you will take the Book of Weapons. Its complete arsenal is yours to use with your legendary skill.