QUOTE (Tarantula @ Apr 22 2008, 09:33 AM)

Per SR4, 132, A. Declare Actions, "The character may also declare one Free Actino during eithe rthis Action Phase or on any subsequent Action Phases in the Combat Turn. Likewise, any character who has already acted in the Combat Turn prior to this Action Phase and still has his Free Action left may declare it at this point if he chooses."
You get one Free Action per IP. You can use it at the same time as you act, or anytime later. You can't use it before you act.
As long as the adept has acted before the mook throwing a knife, (and hasn't used his free action) the adept can declare use of missile parry on the mooks AP, and thusly parry the knife.
Okay, that's a usable interpretation. I kind of thought that's what the text was saying, but wasn't quite sure. Definitely, that makes missile parry usable; I was thinking it was a completely useless power. Actually, I still think it's not all that great, but I gave it to an NPC just for flavor purposes.
Thanks for the reply.