Hello Guardians, I figure I'd post this since most of the guides are outdated and doesn't match with Rise of Iron's Skeleton Key system
First off, we will be farming the 320 version of Restorative Mind. Why? Because the pathing is incredibly easy, and requires little to no effort apart from tight damage at the boss itself.
Before I go into specifics on what you need and damage numbers, I'd like to show you the pathing that you'll want to take in order to achieve a quick & easy time:
Going invisible is crucial as you can avoid a majority of the enemies through the strike, and it's important you abuse the velocity that you obtain with Better Control in order to go as fast as possible.
You can exploit Restorative Mind's eye mechanic by hiding in the position I shoot at after putting in the orb. By crouching and sitting there while you shoot him, he will never close his eye and you'll be able to DPS him down until he's dead.
Now, the following requirements are nessaracy in order to obtain a consistent 5:30 time:
Nightstalker Hunter with Bones of Eao (spec into Better Control, Vanish in Smoke, Lockdown)
Very High Impact Sniper (Black Spindle preferred, Ex Machina / Event Horzion / Devil's Dawn also work.)
Any High-impact primary (Hand cannons preferred.)
The weapons I used and the amount of shots / damage you'll need to deal:
400 Black Spindle w/ CQB: 35 Shots (762,510 total, 21,786 each)
400 Imago Loop: 15 Shots (80,400 total, 5,630 each)
You'll need to deal around roughly 842,910 damage to the boss in order to kill him. Get most of the damage done using Very High Impact sniper, be sure to pop a Special Synth & have Sniper Ammo boots / chests. Finish him off using a primary.
Just to let you know, this can not be done by matchmaking. Why? Because your teammates won't know that you want to exploit the mechanic, and you'll have to spend an extra 1 – 2 minutes making this not as effective. You'll either have to change your date on your PS4 so you'll queue solo or run this with a group, which can go even faster depending on how well your teammates understand this strat.