If character is sorcerer or wizard (with conjuration school) and they possess the feat GSF: Conjuration, I think it would be interesting to let them interact with conjuration items in a unique way.
For example, for reagents that get consumed upon use, maybe the conjurer draws additional strength from the summon focus and all summons are +1. While for summoning times, the conjurer bypasses any negative summon modifier attached to the book.
For example, for reagents that get consumed upon use, maybe the conjurer draws additional strength from the summon focus and all summons are +1. While for summoning times, the conjurer bypasses any negative summon modifier attached to the book.