There was a topic about roc drops a while back by bane_of_Canada. I am not really sure what you should do. Maybe keep a few priests and your pharoe(spelling) there and kill it before it reaches your base and drops off siege. But you are right it is a chicken strat.
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i had my hands full with attacking, and my pharaoh was at my base empowering, but if he sets down the cargo just outside my base it wont make a difference since he has siege and i only have pharaoh and a few towers.
but i know that i will try to devide resource gathering out from now on when playing against egypt, altough then my pharaoh wont be able to enpower it all, but i wont loose everything either if things go wrong.
and it wouldn't be so bad if you could see it comming, but the way you have los you cant see the entire map, so if all else fails, the trip around the edge i usually safe, and you can go that way with a roc and drop right behind the base and destroy a lot before anyone can reach, it stinks.