Maybe its just a skill issue for me, but the spell casting is a bit hard, and the tutorial is lacking. It took me a while to learn how to cast spells, and the spellbook doesn't specify where to start drawing. For example: when I tried to cast the spectral shot, I tried drawing from the outside going inside, but it never worked. Eventually I figured out that your supposed to draw it from inside -> outside.
Overall complex but fun game with good exploration and unique mechanic!