This is not a complete solution phase to phase guide on how to kill the boss but a semi recommendation on how to beat
and to show where his location is.
This can be done in Chapter 14 (replay it in chapter selection if you finish the game) and get the founder king's sigil beforehand (new armiger)
Location of founder king's sigil :
Give an upvote to the person's guide while you are it.
So in Chapter 14, there will be new areas. You will encounter
and he will introduce to a new campsite. Talk to him again he will give you a key and make your way out of there and there will be a cutscene
Location of the boss
X marks your location after the cutscene and the boss will be where I circled. Go up the stairs on your left and pass the enemy base and keep going down the street and a cutscene will start in that area.Now recommendation:
Good news : You can beat him on easy.
Bad news: He is invulnerable to the ring of lucii, so no insta kill
It took me (lvl 120) 45 minutes to beat him on normal by spamming the armiger 3 tech bar move and two summons. The boss was lvl 119, not sure if its set or scaled depending your level. He can pretty much instant kill you with some moves (shoots lasers does explosives). He has a phase where he goes crazy and moves randomly
and is invincible
. He is only invincible when he is not moving and surrounded by the red shield (Credits to Allgorhythm). Just avoid him for a while and let him cool down. There also times where he also goes full on invisible and you have to wait for him to appear again. Just keep hitting him and stock up some elixirs and phoenix down just in case you get into trouble. Hopefully this helps, good luck and all the best
UPDATE : check the comments in this solution by Xboxoholic, Allgorhythm and MuscleSenpai, kudos to them - they provide great tips on how to beat the boss. So I definitely recommend you to read the comments.
Also, in the comments, Allgorhythm has provided the best method to level up and better prepare yourself for the boss. Do check it out if you feel like you wanna level up first beforehand. NOTE : THERE IS A GLITCH WHERE AFTER YOU BEAT HIM, DON'T READ THE Omega's BESTIARY IN THE ARCHIVE SECTION, IT WILL MAKE YOUR GAME FREEZE AND BASICALLY YOU HAVE TO RELOAD ON YOUR LAST SAVE. SO SAVE THE GAME FIRST AND JUST A NOTE THIS GLITCH DOESN'T AFFECT YOUR ACHIEVEMENT IN ANY WAY BUT KINDA A BUZZKILL IF YOU BEAT THE BOSS AND YOU DIDN'T SAVE WHICH HAPPENED TO ME.