This solo mission serves up Hardtack's origin story, and continues the saga of Franchise Force. The plot itself is as simple as they come- Hardtack storms a construction site and slaughters dozens-if-not-hundreds of LEGION goons. You'll start your fight on the lower level. There are hell-, swarm-, blitz- and buff- troopers, but all are low level. Just keep knocking 'em down as they appear.
When you've killed enough, your objective marker will move to the top of the building. Follow it up for another round of massive slaughter.
The strategy is generally the same, though the enemies are bit tougher. The layout prevents them from ganging up on you too much, but it you're feeling pressed, drop down to the under level, and let them follow you one by one.
Toward the end of the regular waves (when your progress bar is around 3/4 full) a snipetrooper will join the fray. This teleporting sharpshooter is ideal prey for your own teleporting harpoon trick.
The final bossy-type is a Tanktrooper Commander. Obviously you'll want to avoid his powerful frontal attack, which will be marked with a translucent beam before he fires. If possible, your want to get behind him to fire into the glowing panel on his back- a weak spot.
Damaging him upclose generates a shockwave which will push you back, but do little damage. Do NOT use your melee or mines if you can help it. If the Tanktrooper gets blown off the edge of the building but does not die, then mission will not complete, and you can't chase after him without leaving the mission area. Avoid this pitfall (so to speak), and kill the tank with basic weaponsfire for mission completion, and new device and weapon skin.