I wasn't even trying to go for flawless raider, I was just doing my weekly solo crota's end grind to get ghorn and HOC(all my friends basically stopped running the raid). It was after I killed the deathsinger and was about to wipe just to not have to deal with the additional adds was when I realized that I didn't die yet. Finished off crota then.....BOOM.....flawless raider.