Not exactly free
Its a great concept, but when I read "Free to play with in-app purchases", I think free to play with in-app purchases *optional*. You only get 3 spells, and you cant get more unless you purchase them with real life money. After 5 minutes, youve done all you can do for free. I wouldnt call that "free to play".
Arah Tinkertoy about
Harry Potter: Spells - Free, v2.2