Some of the issues about it -

When you get a magical book, you can't know how much mana it consumes, you can't know what it actually does and you can't know the different levels do differently except for consuming more mana.

I'd keep that info directly in the item description or something.

What do different levels in different dimensions exactly give you?

How do I use books like Flame breath? It says reqs haven't been met.

How do I fix a broken portal in some dimension?

I've no idea what Awakening Elixir does.