+20d6 at level SEVEN? (is this possible?)

[Tyger]

Yup, you're wrong.

Firstly, Precision Damage, like Sneak Attack, is only dealt on the first of the volley in any volley. So if you can launch 10 arrows, you only get (baring feat usage) to apply your Sneak Attack damage dice on the first arrow.

Secondly, as Magic Missile doesn't have a hit roll, you can't apply precision damage to it in the first place.

So... no, you can't do that.

Granted, you can do several other spells that do have hit rolls (Scorching Ray comes to mind) that would allow you to apply Sneak Attack damage. But no, at level 7, you aren't going to be dishing out 20d6 SA damage.

EDIT: Holy simu-ninja attack of madness!