Yes, they already exist. The Vanguard shells roll w random enemy and location bonuses. You can get them from Nightfalls or Vanguard Rank packages. I have a shell for each enemy type and location, since I have 3 320 shells, I have infused all of these w extra Kingslayers and they are all 315-318. The glimmer bonus helps when grinding strikes or doing bounties, plus the extra materials for picking up engrams at each location keeps a good supply of all those too.