How difficult is this game?

[Taqwus]

Just note that blood magic is different. Non-trivially useful blood-magic magic sites are quite rare. The vast majority of your sacrificial blood slaves will need to be gathered by your commanders (preferably blood mages -- everybody else is bad at it) spending their turns to do so, thus costing you commander-turns as well as a mix of population/income as you patrol to keep the resulting unrest down.

Mictlan (EA,LA) is a bit difficult to start with, as it's completely dependent on blood for even spreading dominion.