An inconsistency I've noted in settings as encountered so far is this: Spells do not use reagents. Reagents are given out as quest rewards and mentioned in some NPC dialog. Other NPCs mention spells that need physical items such as gems and rings. I have yet to encounter an NPC who will answer questions about reagents. I am assuming that they are intended to be items needed for creating, researching, or casting spells and/or creating magic items.
It would be consistent to see some spells that require and/or use up objects when cast. Not too many, mind you, and preferably only higher realm spells that would not need to be cast frequently, such as in combat situations.
