So, I reached over 100.000 miranium storage with that setting:

Putting the booster II between the duplicators did the trick.

EDIT: I beat chapter 12 at level 46 on foot

Please share your wisdom. I keep getting close until you know what happens. Then I destroy the you know what and suddenly a dozen other you know what appear and I rage because it's always at like 10% when that happens.

I also failed at first because I focused on thermal damage (it's shown that he is resistant to that) and looked for the other resistances online:

I equipped my party accordingly and chained overdrives. I was able to kill him before he activated the shield.

If you have an art that deals the damage type of the weapon and you equip a weapon with gravity damage -> art deals gravity damage.

Same with Skells: equip weapons that deal gravity damage and reduce gravity resistance.

Ugh.

Yeah.

Yeah.

Ugh Ugh.

So stay away from thermal and deal as much gravity damage as possible? Okay. I see electric and beam are good to. I'll equip accordingly and try again.

ONE

TWO

THREE

FOUR

Using your tip, I beat him in one try!

...By a hair. I had no access to gravity skell weapons other than what I already had, so I just built an electric set instead. Thank you so much!

EDIT: Ugh, nevermind.

When?

There are 5 phases.

Yeah, I just realized. I died at phase 3. I had no more skells left and there are fucking 10 of the things. What's annoying is that you can't fucking leave to replace your skells between phases, so you literally have to reboot the game to try again, and skip the like five cutscenes everytime. Am I missing something? What kind of ass-backwards game design is this!?

Oh, I thought that was the easiest. They could have other resistances.

You'll need ground gear for the last phase.