First of all, the tone is the "Necronomicon", the most powerful book in the world!
But no, he's not a wizard, just a man with a walking stick. There aren't any wizards in Lovecraft's universe, and all spell involve summoning/control/banishment. Anybody can perform those given the proper books, however, they tend to go insane. In the game version, every time you cast a spell you lose sanity points (you start with up to 100, and it's very difficult to regain).
In this scene, which I won't say much about because it's towards the end, he's going to perform a banishment.
