If you have 4 Dark Stars, you will spike in terms of damage, but you may be lacking frontline if your Jarvan has no items. You can also run 4 Protectors alongside Jhin and Ashe if you feel your frontline is too weak.
Additional comp tips
Jhin, Shaco, and Xerath are all strong carries for this team. Jhin and Ashe are core, but Shaco can also be a carry alongside a unit like Fizz or Ekko. Similarly, Xerath can be another carry if you have extra items and find him 2 star.
We recommend a defensive item on Jhin as with Dark Stars, reviving as the last unit can be a lot of potential damage. However, if you are confident in your positioning, you can run 3 offensive items instead.