I think it would be more interesting if we created AI bots with different mindsets and behaviors instead of just allowing Petra of varying levels to participate in battles. Here's a bot I created based on Petra but with a defensive focus, called Iron Tortoise. It defeats Petra in every battle with its unlimited population and abundant resources. Besides that, I think there should be separate bots with behaviors of nomadic civilizations, maritime civilizations, and possibly more. Everyone is welcome to try them out and give feedback. I'd love to hear your opinions.
bot_IronTortoise.zip