Im on ps4 and on that same exact part.

Just finished that part of the bounty to get the Pocket Infinity (not the other way around ;) lol)). I was a Hunter, and I used the blade dancer's cloak ability along with the arcbolt grenade. You will want to get to the first main section where you face level 28s - you can die here and keep respawning at the beginning of the area. Clear the area, and you'll get about 40 kills. Then die, go to orbit, re-load, do this are again, get your 40ish kills, wipe to orbit, restart, etc etc. Should take you 5 or 6 runs to get it done. 1 - When you get into that first room, your goal is to try and dwindle down all enemies in that room to one or two shots of health before they die, and then leave them. 2 - Once you've lowered a target's health, hide behind cover, cloak, and then pull out your fusion rifle, sneak in behind them, pop one or two of them with your fusion, and then scurry back into cover (or die - you'll restart at the beginning of this area and that's OK - none of the enemies will regain health so you can carry on). 3 - Focus on the red and yellow bar enemies in the middle, as well as the red bar phalynxes on the left. Once you take a few of them down, the harder centurians and colossus will fall back to the top of the ramp and give you some breathing room/ 4 - SNeak up the right side of the central ramp, and use the Hunter's arcbolt grenade to take out the psion's shields. They are by far the hardest things to take care of in this section because they can OHK you, but once the shields are down, pull out your fusion, aim for the head, and they'll be down. 5 - With the centurions, you can take down their shields with a fusion, but damage them with a primary before you waste more fusion rifle ammo. 6 - I had a fusion with solar which was pretty tough, but if you can get your hands on one with arc that will help you out 7 - The idea in this section is to keep chipping away at the enemy's health, and when you have one or two enemies within a shot or two of dealth, cloak, sneak up behind, and get a fusion rifle kill. Rinse and repeat. 8 - Once you complete this section, go into the darkness zone ahead and just die. It's almost impossible to stage fusion rifle kills in the next section because oft he number of enemies and large space in the area making it hard to get up close to enemies for fusion rifle kills. Should take you about 2 hours using the above method. Hope it helps.

I'd offer to help but I'm currently at work. Bring a Arc fusion rifle, I think this week has Arc burn, and just do the first segment of the Nightfall. To clarify, the part where you first encounter lvl 28s. I was one shotting most things that didn't have shields and two shotting the ones that did. Occasionally a third will be needed on Colossus and Major Centurions.