I made a ranty post about the lost sector being too difficult/annoyingly difficult, however as always the combination is that does the trick. This is for 10 under LL.
I tried multiple variations however this is most consistent:
Warlock (Well of Radiance) Nade: Solar Flare
Kinetic: Cold Denial (mine was with KW and MK for extra punch)
Energy: Seventh Seraph SMG or IKELOS SMG (Warmind Cell build as well as Arc for shields)
Power: The Lament (it shreds Champions and Bosses)
Solar Flare very consistently disrupts the many Overload Champions. Well of Radiance gives you the survivability in the Boss Room, as you will have a hard time otherwise.
Additional Mods included Protective Light just to be able to tank a bit more damage, Global Reach and optionally Lucent Blade. You can focus on Sword Finder/Scavenger, as you don’t need Special Ammo. Use both Armour Piercing Mods for Pulse and SMG as well as Thermo Overload and Surge Eater, so you get your nade back after each disrupt.
Take out as much as you can from afar with the Pulse Rifle in the first room. As soon as the Champion pushes, disrupt, jump with Lament and melt him. You will want to back track immediately, as you will take damage from ads there. Use your nade to destroy the fire shield on the big shank.
Then go methodically in the next room, take out the captain and dregs on the ledge on the right after dropping down behind cover in front of the barrier servitor.
After that hit the servitor to make the shanks and dregs loose immunity and clear as many of them as possible before killing the servitor. Lament make sit doable to “stick” in the air and damage the servitor. You might die as a result, but if you kill him it’s a good revive trade. Take out the dregs on the next platform, jump there and go behind cover. Stick the Shank with your nade, kill it and while you wait for the recharge kill the vandal in front of the section shield. Then disrupt and kill the next overload.
Use your SMG to clear the next mini room, drop down if the get too close.
Jump up on the ledge which will make a first round of exploder shanks spawn, burst those with the Pulse and try to take out the vandal at the end of the corridor. Jump to the ledge which will spawn the next round of exploders and kill them with your SMG. Use your nade on the Overload and melt.
In the boss room, clear the 4 wretches. Once you cleared them the boss will spawn. You will want to place your well in the round middle part just after killing the last wretch to be faster than the boss. Melt with Lament. Try to get about 2/3 of health down and kill the ads with your sword in the well. You should have enough ammo. Try and kill the servitor that spawns if you can before you die. Respawn, drop down and use your pulse and SMG to clear out a good portion of ads then rush the boss and try to damage as much as possible. Rinse and repeat and keep an eye on the timer. Feel free to use 2-3 revives here as it’s the last part. You shouldn’t need much more.
Have fun farming, the drop rates are really not good lol.