I've seen a couple of posts on Reddit about this, but I couldn't find any on the forums here or in the Known Issues, so I'm posting this here hoping someone will see it. When you shoot an enemy with Forerunner, then change targets, the initial enemy will regenerate a decent portion of its health. In Duality specifically, if you're shooting a Bellkeeper and you have to turn around to shoot at something else, instead of 3 crits it takes 5 to kill. I've noticed this glitch in other places too, but the clip I've linked is in Duality. Also, this isn't an issue with lag on my side, Forerunner is the only gun I've had this happen with. I do remember a similar glitch happening a lot with Sleeper Simulant back in the Leviathan days, where you'd shoot a bather with it and half of it's health would rubber band back immediately. Edit: I'm paying more attention to it while I play now, enemy health also tends to rubber band when you just stop shooting for a bit, so it happens a lot while reloading.