I've wrapped that into some reply the other day. But I really can't stress enough that I do think that Mages are becoming available way to early into the game.

Due to the fact that magic apparel like cloaks of 50% fire/cold restistance are becoming available much later than Mages, it is quite easy to mop up entire armies with a hand full of Mages in the early game (not that the AI would wrap it's troops into those cloaks anyway...).

So, maybe it would be a good idea to shove them up the tech tree a few notches, too.

Btw.: If you send a couple of mages with the (I think it was called) Dark Ritual trait like Gravewardens out to kill mite mobs or wildings your rmana pool turns into a mana ocean.