Just wanted to suggest adding a mode, where you could transform the spellbook into a locked version with 1 spell assigned to left click and a second one on rightclick (when book is selected). I've noticed in basically all magic-based mods the downfall seems to be spell switching. If there was a way to transmute/transform the book into a wand/sword/magic pick/whatever and have pre-assigned spells, it would let the user have 2 pre-defined spells equipped until he transmutes the "whatever" back into the book.
The reason im suggesting this, is because this would make it perfect for mining as an example. Break on left click and light on right. There's probably a million more examples, but ill stop at one.
This could potentially be done as an unlock on getting the 2nd spellbook or research or a special glyph and so on. Maybe even let the book transforms give minor benefits to mana or damage or other stuff. Basically pro's and cons by going standard book or a transmute.

Just wanted to pitch this idea, but I have no clue how hard something like that would be to implement. Also, I think the idea popped into my head when I saw Dire try to dual spell in the nether and get repeatedly pummeled by basically everything on the forgecraft server :D