Tactics for the Stronghold.

I think using Krags is a bad idea because you need to give them a good buff before they can really be effective. A Krag that gets caught in a mass slow from an enemy mage might not even reach the enemy units.
I'd prefer Gundulls. If you quickly create Behemoths, you've practically won, because -40% (80%) armor, even with a not-so-developed attack, is very damaging.