Ok Dr. Strange narating the fight says that big G dismissed Agamotto as unworthy due to Agamotto being in a silly caterpillar form and that big G was out of his element and in Agamotto's and that might make all the differance. If it's in Agamotto's realm then big G can't possibly win or even do any lasting physical damage. Agamotto reformed instantly in that fight and only seemed concerned about his possessions being collaterally damaged. Out of his realm its a different fight possibly. Now how is that differant than any celestial fighting Agamotto?