Ok, so I don't expect this suggestion to be taken seriously but I've thinking about reconciling blood magic costs with gem based costs and it occured to me what if they used the same metric and non-unique blood summons cost gems, not slaves? Because so many blood summons are cross path it would be easy to assign the appropriate gem type for most of them. Then you could ask, for instance, how many E gems is a demon knight worth compared to the other available E summons? For single path cases like fiends of darkness you could have a couple of versions of the spell using different gem types to keep the spell available to most/all blood nations. Ritual of the five gates maybe just go with S gems (probably do the same for send horror even though it's not a summon).
National blood spells could take the same approach, generally matching single path blood spells with that nation's dominant paths.
Added bonus: reduced micro since you'd only have to blood hunt to the extent of fueling battlefield magic, blood sacrificing and summoning uniques. Sure, blood nations would have to pay "real money" for their summons but OTOH they'd have some extra gold from not hunting quite as many provinces. Though if they did keep hunting to the same degree it would be interesting to see how that translated to additional power on the battlefield (more life for a life casters, etc.)
And yes, they likely wouldn't have the gem income to mass the numbers of blood summons they have now, but that just puts them on the same footing with non-blood nations.
Like I said, I'm not seriously suggesting this as a CBM change but maybe one day I'll run an experimental game with these settings.
