The Index (Easily)
This section covers how to easily complete The Index. Credit to Danish Chief#7899
Lets start out with the gear that is recommended. Firstly, you'll want to complete The Sacrifice to acquire Excalibur Umbra. The reason why you want to use Umbra is because his passive is when entering your Operator, Umbra will turn into a Specter AI and kill. Secondly, A lot of weapons will work well with Umbra's Specter, Even though this is the case, There's a couple top-tier ones that are recommended to use, Those being:
  • Kohm
  • Rubico
  • Tombfinger (With Haymaker + Splat)
  • Catchmoon (With Haymaker +Splat)
Thirdly, You must know how to build for these weapons, Since the enemies in the Index have Alloy Armor, you want to build for Radiation, so 90% Electricity 90% Heat. You also want to build for crit, so use those mods as well. For the Kohm, You also want additional fire rate, since Umbra has infinite magazine with the Kohm.

Inside Map:

For this area, you’ll want to head to the enemy side of the map (the one that’s chrome/the one that you put points on). Once you get there, there’ll be a ledge on top of the hallway leading to the staircase. You’ll want to stand on this, then leave umbra. This will teleport him below, on to the bunker protecting the place where points are scored. Once this has been done, you have to look within the area which I marked below:

How it works:

When you look at the places which I explained and marked up top, and don’t move your gaze away from said area, you force the enemies to only spawn in one small area. When you do this, you can use umbra’s innate ability to hit all shots without damage drop off to effectively slaughter them where they stand and get an insane amount of points to drop. The way you actually get to score points with this method, is by letting the specters pick up the points and run them in.
Note: The Wukong specter doesn’t pick up points and tends to be utterly useless, as well as the fact that some of the specters sometimes get stuck. This can be undone by just going down from your spot most of the time, but sometimes they need you to run in points for them.
Note on focus school/operator arcanes: I recommend using Unairu, so that when need be you can make your umbra invisible as well as giving him an 80% damage reduction. Secondly, due to my use of invisibility to keep him alive I recommend using magus repair to heal him 20% of his max health while you’re keeping him invisible.