The best way to destroy the rest of the Legion's supplies is to use their own weapons against them. I've been working on a rig that will let you take control of one of those Fel Reaver Sentinels below.
There are a couple things I need to work out, yet. For that, I'll need the manual that Doctor Maleficus keeps locked in a chest near the bottom of the ramp. He probably won't give up the key without a fight, so you'll need to capture it. Bring the fel reaver manual back to me and I'll do the rest.