I think you should make a mutation where 4 tanks and 10 survivors are in some sort of bowling game and you would have an insta-death in the back so if you hit a survivor with your "bowling ball" (rock throw) they would fly into an insta-death area and for the survivors they need to dodge the bowling ball like pins with legs and after the two "balls" are thrown a defib is given to each survivors and then the survivors that died teleport into the lane and get defibbed by teammates. Game ends when all survivors are dead or when all tanks get all of their throws
Then the final battle will commense one tank at a time will attack the survivors and the survivors will have no ammo when the mutation starts but then there will be ammo that rises and everyone gets a chance to get the ammo, Really cool idea on my part and a good idea for you Rayman