In the Mako Reactor Boss Fight with the Dragon Fly and the Gargoyles wait for a gargoyle to fly over the platform your on and shoot it down with the machine gun DO NOT KILL IT, instead jump onto it's head and it will fly carrying YOU for an aerial assualt against the dragon fly. IT will eventually fly all the way around the reactor and back to the platform just shoot it again to land or jump off when your back to the platform. Keep it down or wait for another to repeat.