One of the best ways to address drop pod armies is to turtle up in your deployment in order to minimize the the number of targets that are without cover. Following that, it can REALLY piss off a drop pod player to just move away and flat out in order to get as far away from them as possible. You spend the turn redeploying/flatting out instead of shooting; however, it also means your opponent is now walking across back to you.
Personally - the Void Shield isn't worth it since it relies on you having a fairly static army (though the 12" radius it produces is decent). Also - if you use the redeployment strategy I mentioned, then it gives your opponent a bubble instead.
If you want to run a fortification against a drop pod army, I would suggest a Skyshield Landing Pad. It's large enough to fit a LOT of your models on it. In addition, it's raised up, meaning it's harder for your opponent to see units if you make it so there is no place for him to land on the skyshield itself. Futhermore, it provides a 4++ save to everything on top of it if the guards are up.
Beyond that, I can only recommend that you don't fire off your serpent shields and (if you haven't done so already) post over in the Eldar forum for some potential additional tips. If you were running DE (or at least just the Scalpel Squadron formation) one option would be to do a null deployment; however, that's worst if you aren't going 2nd.