First post here, so bear with me.

Seen some people struggling to clear this so I figured I can put up a guide video on how to clear it (with alternative options!) on basically F2P gear.
Only TM if you want to call it that is Mechanical Heart and Minfilia's TM (both were free). There is also dark resist materia in the Mog King shop right now.

Team:

iNichol - Lakshimi for confuse resist. Max SPR, at least level 20LB High Tide. LB fills about 45 MP per turn which covers everyone's most expensive skills.
Earth Veritas - Max HP/DEF, Blind Resistance
Ashe - Diablos Blind Resist 100% Dark Resist. Has to have highest ATK to get targeted. Wind Element for chain.
Ashe - Wind element weapon for chain
Friend Emperor: BiS :) [I used my own, but you get the picture]

For those that don't have iNichol, you can do Tim Rosa and get the same result, no 5 man mission though :(

Video link: https://www.youtube.com/watch?v=V7uQULBPF9w&feature=youtu.be

Due to popular request here is a video without iNichol. All missions, no Mechanical heart TM)

Link: https://youtu.be/gDTXglSMB6o
Team (Tim, EV, Ashe, Yshtola Friend:Emperor)

-Caption: I got lucky at the end because I forgot to do Tim's LB and I almost got wrecked, but if you do it right, no one on the team should die

Guide:

Turn 1

Nichol: ATK/MAG Break Cover on EV
EV: Guard
Ashe 1: Osmose
Ashe: Dodge item on EV (Not necessary) or MP drain
Emperor: Dual Cast Osmose

Turn 2

EV should survive by like 40%, pre-nerf it would survive as well.

iNichol: LB or Mirage on EV
EV: Break Resist
Ashe: Heaven's Fury
Ashe: Heaven's Fury
Emperor: Dual Cast Osmose

Turn 3

iNichol: ATK/MAG Break Mirage on EV
EV: Cover
Ashe: Heaven's Fury
Ashe: Heaven's Fury
Emperor: Dual Cast Osmose

Turn 4

iNichol: LB
EV: Break Resist
Ashe: Heaven's Fury
Ashe: Heaven's Fury
Emperor: Fire from Below

Moving on, just rinse repeat till you are about 60%. I messed it up a bit in the video (got it to 59% by accident!), but essentially you should aim for this 3 turn rotation.

iNichol: (1) Confuse resist, (2) ATK/MAG break Mirage, (3) LB on the turn you cross 60%
EV: (1) Cover (2) Break Resist (3) LB on turn you cross 60%
Emperor: (1) Control (2) Fire from Below to manage life just before 60% (3) Cap with Fire from Below to take down to about 20%

With Ashe you need to use Sword of Kings to be able to elemental cap with Emperor instead of Heaven's Fury. Since Fire From Below is a 1 hit move it should be extremely easy to do.

And that should be it, there is no way you will die with EV LB iNichols Mirage when crossing threshold. If MP is drained to much, you can carry an AOE MP healing item like shown in my video. Just make sure you kill it again on the next turn.

All Missions complete!

This being a gacha game, I understand not everyone has all these characters, so I'm going to post some alternatives at the top of my head that might do the same purpose:

Replacing Ashe/Ashe:

Luka (or Yshtola) Acid Rain Materia / Capper that chains with Acid Rain (Gouken?)

Replacing Emperor:

I recommend some sort of DW Ashe in this case, but I think Emperor is just the easiest for this.

1) Runera (Cap with Gleaming Arrow, use Ashe to buff MAG?)
2) Light Veritas (must account for Blind) You can try to get the ~100% light resist on the magic spells to make it easier.
3) Luneth
4) Fire Veritas with Fixed Dice
5) 2B with Fixed Dice

Hope this guide helps people who haven't been able to clear it be able to achieve this more easily!