I'm pretty sure Insane Difficulty with 10 Insane Opponents is impossible without attacking strategy. Maybe Binding and one at a time early strikes on opponents would work though, maybe Tuidjy's combo will do it.
I had Enchanters, Master Scouts, Defensive, Betrayers, and Scholars (and the 4 weaknesses). Even though I levelled up a number of Henchmen, and my Sov was high 20's level by the end, and I ended up buying 10 powerful units with Silver Tongue and high Spell Mastery, they just kept on attacking my with too many units. They get so high production bonuses that even with 60% unrest from capturing my towns, their production bonus by itself exceeds the unrest penalty. My Sov had Inpenetrable Tower Shield and heaps of other stuff, but they just kept attacking me with armies full of huge HP ice shooters. This was the best Insane 10 AI game I ever had, yet Magnar could just keep spewing out new troops and attack me multiple times each turn. I had 5 towns and pretty much all the reasonable luck I could get, yet Magnar simply outproduced me (which is not surprising, considering the production bonuses). If you truly have 10 Insane AIs to go against, I think currently it is impossible to win. IMO. ![]()