Fighting the Legion

So we have that Legion player at my FLGS. He seems to have decided he wants to play me again in our stores league, and has decided he will hand me my first crushing defeat this season. So I am sitting here trying to figure out what to do against such a foe.

Gdaybloke of Lost Hemisphere has been giving me all sorts of tips to use with Grim (such as remembering to use the Tether Gun for one!) and also pointing out I shouldn't play a Grim list like a brick.

But I was hoping some of you all out there gentle readers might have some more general tips in regards to dealing with Legion. Like what kind of nasty tricks should I be watching for?

Also, I am wondering if I should wait till I have a heavy before playing again. I really could use a heavy beatstick.

EDIT - Its a different legion player, but the issue still stands on what to do against legion :P