So Astarion is a ranger in my playthrough with sharp shooter, that's where the +10 came from (I forget to turn it off for the picture). Yes the enemy was asleep so auto crit. The bow does +D10 extra on a crit ( not 2 D10). Larian has already worked that out.
Its not datamined just part of one of my mods. Obviously it's just me making the dos2 weapon using 5e rules.
I'm thinking of adding a ring that allows you to summon your soul wolf as well.