Destroy the Core, one team defends the core from damage,other teams trys to destroy it. via some item, like the rpg pickaxe (since it comes with it's own events)
4 doors and some cover from the top,
think sniper vs runners but vertically, the core would have to be completely exposed tho (for obvious balance reasons)
once said core is hit x amount of times, that team wins and teams shuffle rounds could last 3 mins or something
