Wisdom on Pyrithum killing?

[Saxon]

In a match against the computer, in the early expansion phase, I attacked some independent Dark Vines with the bulk of my forces. I did not know they were so strong….

Result: I am behind. Actually, I am number two out of six, but Pyrithum is a very long way ahead. They got some hydras early on and swarmed all over the independents. I killed those, but they have a big lead in everything except research and gems. I am Mariagon with a level 9 Great Sage Pretender. Perhaps not the best choice, but I wanted defense to beef up my Flagellent holy units and was sick of being behind in research.

My question is, how do I beat Pyrithum back down to size? As another threat states, they are pretty well rounded. I am hopeful that they are running into other nations now and being slowed down. It is a big map and hope that their expansion will be limited as they fight everyone at once. I have also gotten a foothold in the oceans and expect to be able to take all of them. With the flying units, it is cheap to get a small group of effective patrollers and then max the taxes. However, I was hoping for some nation specific take down hints from your collective wisdom!