I find the current set up for setting a Friendly Challenge are not fair & even.
When someone sets a friendly challenge. It is not fair that users that are at higher levels than the user setting the friendly challenge, are allowed to attack a user at much lower levels.
When a user can wipe out a city that is at the Roman/gunpowder when the attacker is at modern war fair levels.
It should be set up that only users at the same historic level can attack cities/users within their same historic level.
When someone sets a friendly challenge. It is not fair that users that are at higher levels than the user setting the friendly challenge, are allowed to attack a user at much lower levels.
When a user can wipe out a city that is at the Roman/gunpowder when the attacker is at modern war fair levels.
It should be set up that only users at the same historic level can attack cities/users within their same historic level.