Hmm, you can do a dummy unit and when you use spellbook (when you click on it ^^ after replacing it by an active spell) just let select the dummy which have the spells (with placements). You can also transfer every order to your hero (and add an hidden spellbook which contain the spells of the dummy). ANd like this, if oyu use for example a spell, just low the mana of your hero.
You can also add the model of your hero and all the stats of your hero (items include) on the dummy, to see no changes.