[PvK]

I don't think Order is as important as Production for MA Agartha. Magic is good for research. You don't really need archers to expand if you learn how to use heavy infantry well (see, "playing an Ulmish nation"...), though you might recruit some indy shortbows. One good early research goal IMO is Legions of Steel, though again that means learning to use your heavy infantry well. Fire Brands and Frost Brands give you thugs but removing the need for high Attack skill from your giants.

Don't forget that if there are water provinces in reach, you should be able to take them easily with a few turns' recruitment of your armored amphibian troops.