I am running a Adventure League game. I am allowing him to bring 5 skeletons to help out the party. The skeletons will be doing average damage. They have long bows. 1d8 damage. Silver tipped arrows. No extra damage. He is doing 10 average damage per hit using his stat bonus to hit and damage. I think his damage should be 8 (1d8 +2). What is the correct formula?