Totally useless.

I would like it if the book was tougher and had some effect similar to avenging angel when it takes damage.

like a brontor but with ranged retaliation

I wouldn't mind if it just auto cast spells each turn, but without your control. Valuable uncoordinated second caster, that might accidentally fireball your troops. Could be an interesting balance point.

As it is now, you get a slower, random, version of one of your other spells, and pay more mana for it too.