Gah! Forgot that I can use Biting Swarm as a ranged basic - so can we say that Galadren used that?
If so, if 18 hits Sinruth he takes 6 damage as above and takes a -2 penalty to his to-hit rolls for the next round.
If it misses, Galadren will use Inevitable Shot encounter power to redirect the bolt to his buddy in J11.
Redirect To-Hit:
Rolled 1d20+9 : 18 + 9, total 27
If hit, hobgoblin buddy there takes and a -2 penalty to-hit until Galadren's next turn.
Damage:
Rolled 1d10+5 : 3 + 5, total 8