Barbarian Breakout (Allies)
Invest in a Citadel early on.
City Hall first. Castle walls and at least 3 different stacks by end of week 1.
Barracks and Monastery on days 6 and 7.
I was able to hold the barbarians for about 1 months, including decimating the strongest starting barbarian without having to go down. The frozen land to the south does some help in delaying their attacks for a day or two which help a little.
Mighty Gorgons. Nothing higher.
You play it with towns which are cheap and easily defensible. Your best shot might be Rampart, Fortress or Castle. I prefer Fortress because then you got no moral penalty if you combine your troops with whatever remaining in the barbarian's stronghold once you capture one.
Don't invest too much in your town. Try to get into your enemies town instead and buy from their towns. By this, you deny them their weekly monster allowance and capitol build as well.