Natsu's power

i decided to re-watch faitytail and I came across the Natsu vs twin dragon fight and i thought what natsu power would have been if he decided to use the flame lightning dragon ability and dragon force at the same time. How much power he would make just by using them with the power he had in the fight, I know it isn't the hardest fight natsu has been in but I came to think of this as he beet two dragon slayers with dragon force