Take the easy way, Get a friend in Co-op and have him play it on casual. It is 10x easier since the Locust for him have casual health and casual damage. I would help but my X-box is getting repaired for E-74 error... Difficulty only changes your own health, not the enemies. Wouldn't changing your health be the same as changing the damage they deal? If everything does double, that's the same as having half health I would think. I think higher difficulty enemies have better accuracy, and damage. Enemy AI is constant across all difficulties, or you wouldn't be able to have 2 people on different difficulties at the same time.