Mictlan poses problem to anyone.
But think of it - to kill vans with lots of small units and devils, you must catch them first. They are stealthy and they just ninja your provinces (which have a terrible PD btw). Also, vanheim can wreak havoc amongst your jaguar warriors with bladewind and wind guided indie archers. What can your mages do against the van sacreds?
P.S.
To think of it, as Mictlan you have these2xblessed bats, it may be too much for the Van. Not in MA though, when blood magic is banned by Lawgiver.)