Middle-earth Extended Edition is a project with the goal of expanding the game with new units, heroes, spells and factions as well as adding unused features existing in the game and bringing more realism to its combat system.
For the full list of changes related to the Spell book, please read the 'Rohan Update' news article in the 'Articles' section.
Sweet, are we going to get a release soon?
Not until summer sadly, as I'm on my studies now. A good thing is that you will be getting a fairly large update :).