Here’s the Hound, not wearing a helmet. That guy’s not wearing a helmet. This guy just had his head smashed in, he wasn't wearing a helmet. That one, the guy that got his throat slit, if he had been wearing a helmet, that wouldn't have happened. I’m wearing a helmet right now. Everybody should wear a helmet... There once was a Superbowl where Thurman Thomas, of the Buffalo Bills was going to be in the Superbowl, but he was unable to find his helmet, so he didn't actually start the Superbowl game. Shoulda had his helmet... See, see Tyrion there? He’s wearing his helmet... but he just took it off, and as you see he’ll rue it... That guy should have been wearing a helmet.”
"So our success condition here is 'angry swamp monster hiding in the sewers'."
"And we're sure we're the good guys."
Your helmet is a masterpiece of UNSC military technology. Motion tracker, VISR tech, vision modes and HUD for offensive capabilities, while defensively, it is heavily armored, projects the cranial energy shields, and protects you from radiation, vacuum, chemical, and biological attacks. None of which will help you if you do not have it on. Which the Prometheans took advantage of. As would any competent enemy.