[Dedas]

I agree with above poster. The infantry is so cheap you can field great numbers of them in a hurry (just like the soviets did in WW2), not to mention the ease to boost them thanks to great magic diversity. This should not me overlooked I believe.
The milita actually have rather nice stats if you consider the price and thus the number you can hire. The only low point is morale of course, but that could be dealt with some excellent morale boosting summons and other units with banners.
One should really take advantage of the fact that they all have frost resistance meaning that they do not take the encumbrance penalty for extreme cold (-3). So try to fight where your dominion is high; use your rather cheap and excellent priests for preaching.

Some tips:

1. Do a fast expansion, grabbing lots and lots of territory with your awake pretender.
2. When war is declared let the enemy come to you and slowly wither them down with low cost troops. Making them pay dearly for every inch of ground. Hit the provinces with freeze spells if they aren't cold enough. Use your stealth units for partisan attacks and raiding.
3. This strategy will buy you valuable time for research and heavier troops. Because back in your empire you are building heavy cavalry and summoning birds and three-headed wyverns.
4. When the time is right, hit the enemy rear with the shock troops and continue on towards his capitol.