Arena , teamwork and bullying culture? Arena shards switch up

If you wanted to prevent collusion, switching up every 6 months wouldn't do it.

Having a ranking system where you are attacking blind (That is, you don't know what target you're attacking until the battle starts) and then gaining/losing rating based off how your team does on offense (and maybe defense) would be the way to prevent collusion... and that would require completely rethinking how Arena works.