1) Fast travel to the Dust. Grab a car and head Northwest to Eridium Blight.
2) When in Eridium Blight, follow the road. At one point you'll see a closed gate on your right and a bridge off to your left. Go to the closed gate and it will open when you get close enough to it. Keep following the road. When you get close to the drawbridge to Arid Nexus, it will retract and Brick will tell you it's time for Plan B.
3) Head back the way you came, and this time your going to cross the aforementioned bridge. After the bridge veer left, so that the lava is on your right. You'll see a overhead bridge, make a sharp right into a mineshaft to travel to Sawtooth Cauldron.
4) Upon entering Sawtooth Cauldron you CAN fight your way through a ton of bandits as you work your way down to their hideout OR you can walk along the cliff to the right of the vending machines until you see 3 or 4 tusks emerging from the cave. Drop down right there, and you're instantly at the cave with only minor enemy attacks!
5) Fight your way to the elevator that leads up to the Buzzard Nest. There you will be attacked by 4 Ambush Commanders. Upon their death, their leader, Mortar, will decide not to ride down to meet you, thus leaving the elevator still not working (d'oh). So, time for Plan C. blow up his buzzard and MAKE him come down to see you.
6) Head towards Cramfist Foundry via Main Street Reservoir. You can go either way around the mountain in the center of the screen, but the left is advised (the more civilized side) as the right side tends to spawn Badass Pyre Threshers.
7) Fight your way into Cramfist's foundry and disable the gun turrets (and probably quite a few buzzards as well). Make your way up to the center and summon Boombringer, Mortar's buzzard. Blow it up, and walk away without looking at the explosion (baaaaaadass man).
8) Now head back the way you came, but kind of veer to the left. You'll see a conveyer belt which dumps back into the cave you want to go into. Ride it in. Head back to the elevator, which Mortar has already ridden down. He's an optional mini-boss, but I have to say, if your at level, he's kind of a pain in the ass. I died several times before I just laid into him with a rocket launcher and won. So.... your call whether it's fight or flight.
9) Ride the elevator to the buzzards nest and kill 5 buzzards. Clear out any ground troops as needed (they are not an infinite spawn). After the buzzards are down "mark" 5 boxes as the Slab's pick them up.
10) Take a leap off the east side of the Buzzard's nest as that will put you back onto the same road you walked into this level on. Fast travel back to Eridium Blight, go back to the drawbridge, and this time it'll work. Drive across the bridge into Arid Nexus Boneyard, turn in the mission to the holographic intercom and
"Bombs Away" 20 Gamerscore.