You'll get this mission immediately following the completion of "Best Minion Ever".
|Normal||True Vault Hunter|
|Gear:||Assault Rifle or Shotgun||Assault Rifle or Shotgun|
Use Claptrap's boat to travel to Three Horns Divide. When you disembark, head NW. You'll head under a large bridge and encounter about four Bullymong Adults and Monglets. Walk past them and you'll come up a ramp. At the top, you'll be attacked by another group of Bullymongs.
Your waypoint will lead you up to a Catch-a-Ride station but you won't be able to use it. You'll have to work your way through a Bandit Camp nearby to collect a Hyperion Machine that can be used to bypass the lock.
The camp is going to have a variety of Bandits including Psychos, Marauders and possibly even a couple of Nomads. It's best to hang by the front of the camp for the most part because if there are any Nomads, they are going to be tougher than you are used to and probably carry close range weapons. Eventually, one of the Bandits will drop a Hyperion Adapter. Take this and attach it to the Catch-a-Ride station. After some hacking, you'll be able to grab a vehicle.
Drive out from the camp towards the bridge you went under earlier. You'll have to hit the turbo to get over the bridge because it's not complete. This will bring you through a cave that's filled with Bullymongs but they shouldn't be able to stand up to the weapons on your ride. You also have a good amount of protection so you could also opt to drive right by them. When you come out, you'll come to a plain that, while frozen, looks a lot more like the Pandora you may be used to. It's much flatter and filled with Rakk and Scags. Plow through these enemies until you come to another Catch-a-Ride station. Stop here and investigate to find some vending machines and a fast travel station.
When you go past the Fast Travel Station and vending machines to the west, you'll eventually go through a small tunnel and come out to another area. If you follow the road, it will take you past a couple of wrecked Rides not far from a Bandit Camp. Next to one of the rides on the ground will be an the Echo device of Corporal Reiss.
This will reset your waypoint to on top of a small mountain. Follow the waypoint to Corporal Reiss' location and you'll find him being attacked by Three Psychos. Kill them all and he will tell you about the core that you need to find. After you talk to him, make sure you look up to find the Rakk that should be headed for you.
A new set of Waypoints will appear on the map that lead you to a nearby Bandit Camp. You have two objectives here though one of them is optional. The optional mission is to kill 20 Bandits in this camp which you'll come close to while trying to go for the Main objective. The main objective is to collect the Core that the bandits stole from Corporal Reiss. Which bandit will drop this is likely random but usually happens after about ten kills or so.
You're going to run into a fair number of Nomads, Psychos, and Midgets in this camp. Be sure to watch for Badass Psychos as well. There may also be a couple of Marauders but they're going to keep furthest back in the camp. The best thing to do is head towards the camp but before you go in, stick to the left wall and back up a little. Eventually, the wall will curve back to the right and you can get into a little nook. From there, you can shoot between a pipe and the wall. You'll be completely safe from this position but you'll be able to deal damage with ease.
From this position, keep killing bandits until you've run out of bandits to kill. There are more inside the camp that may not have spawned yet but you'll have to move into the camp to get them to spawn. Grab the core if it's been dropped and then continue killing Bandits to go for the optional objective. If you go in and get ambushed, you can always retreat to your safe spot.
With both objectives in hand, hop in your ride and follow the waypoint to Sanctuary. When you get there, you'll have to talk to a guard on the wall. Talk to Lt. Davis and he'll have you insert the core into the nearby machine. After that, he'll direct you to the gate and you'll be let into Sanctuary.