i've seen this on under quite often so it's not my idea, but i've never seen it posted either. i was playing once as nod and the gdi had several tanks outside the base, including one that was doing nothing but firing it's missiles into the nod's tunnel entrance. nothing could come out and the harvester was toasted time after time. needless to say it was very frustrating for my team and the gdi won easily. just remember to have some engies repairing you constantly cuz i guarantee the enemy will try again and again to break the siege...