Allows you to choose RaceMenu overlays to only show up when you're fighting, as well as offering a selection of particle effects to use in or out of combat.
I've recently bumped into this little mod here. It basically just adds a toggle that makes it so that specific RaceMeny overlays you pick fade out when not in combat and fade in when they are in combat.
Very nice, I'm currently building a new mod list and plan on playing as a Nord shaman type character, this will definitely aid in the feels on that front.