I'm not sure if this is a widely known fact that I've missed but this is something that I noticed while beating the raid for the first time on hard: If someone dies and your team is going to wipe, don't get killed by the Oversoul because you will lose about a third of your Super when it's fully charged. Instead either kill yourself or by any enemy and you will still have your Super the next time you spawn. Hope that little tidbit helps and good luck!