B skill for a guard bow L!Lyn

So I have a neutral legendary lyn, and while +def might be better for it, I wanna see how she does using Guard bow+(def) and laws of sacae together. With a speed at 36 base, assumedly 40 most of the time thanks to her A skill and potentially higher if she's ona team that gives her some support, I don't know if QR that I would usually put on a defensive unit is the way to go. I've been thinking Promoting Lyon for Guard 3 might be worthwhile? Possibly bowbreaker, but I feel like QR would be better since her speed is high enough that she shouldn't fear doubles from too many units. I don't have anything 5* exclusively available for it either, just common stuff since I'm still only really checking out how well it'll work.