Wow, what seemed like it was going to be a pain in the ass, turned out to be probably the easiest Nightfall ever to solo. Instead of waiting for my lunch break, where I try to run the Nightfall with my friends on their lunches, I took and early lunch and went for it solo.
Ok, here are my pro tip/cheese factory for solo.
1. Ice Breaker or lots of Special Ammo Synthesis. A fully leveled IB makes this cake
2. Run past all the encounters until you get to the area where you fight the Lieutenants.
3. Stay back and just snipe everything. You can head shot Phalanxes by aiming in the upper left corner of their shield and timing it with their breathing. They ever so slightly expose their heads in their breathing animation
4. The first bunker area you enter for the Lieutenant battle, where all four of the rocket sparrow vehicles are. As you go out into the open, look back and there is a huge awning to the entrance. You can jump up the angled edge of the awning and then onto the rock ledge and back on top of the awning. You can clear out all the mobs from here as well, but it is also a perfect tank cheese spot.
5. Cheese the fuck out of the tank from the awning. He will never even shoot you (he never shot once at me. This might not be 100%)
6. Sparrow your ass to the next section. Take a quick look at the area, it could be cleared out as other public players will be in this area. If not, take it slow, or snipe most dudes and sparrow past them into the ship and up the ramps.
7.Room before Valus, take it slow, no need to die here.
8. That box as soon as you entered that
Somewhatgroovy shared in this video is the perfect spot. Thanks dude! So much better than the other spots. It is the easiest place to ever get to and you just hang back, pop out and snipe Valus when he is at the far end. Manage the adds, only occasionally will the jet pack cabal guys fly over to a line of sight where you have to shoot them. The Psions or Phalanxes never path find to the side of the crates. Take your pop shots at Valus, run back to boxes. When he comes to the near end, do the same, unload. Rinse and repeat and keep the adds under control.
I wore him down to a sliver of health solo, then invited my two friends in for the 10 seconds of effort to kill him off. I got the Admonisher III legendary void rocket launcher, so I am happy. I needed a void RL to complete my elemental arsenal to have a legendary sniper and RL of all three elemental types. Has the lock on perk too, neat.