This battle is set up in a 3v3 format with the home faction set as Poland, though all armies are playable. Choosing a Polish army is more challenging than one of the Mongols. Your spear units will not be flattened by a cavalry charge as they are exp1 and armour1 as a work around for the shield bug.
I purposely made smaller armies rather than all 20 unit in a bid to prevent lag for as many people as possible. There is a readme included in the Zipfile with relevant details and a description of the battle. I hope you enjoy it.