Following the dramatic events at the end of Chapter 15 and the start of this Chapter, the Bionis will be under attack as Telethia swarm everywhere. Once you regain control, you’ll be in a short unwinnable battle against Zanza. You don’t need to deal any damage to Zanza, simply surviving is enough for the battle to conclude and you have control of Fiora only.
Once the battle concludes, more scenes will take place and once you regain control you’ll find yourself in the Mechonis Core with Shulk leaving the party. If you’re not already using her, consider placing Melia as the party leader, she’ll be useful for the upcoming battles (ensure she has Mind Blast set). Use the Transporter and head back across the Bridge to Apocrypha, then follow the pipes back to the south to reach Junks. Make sure you’re fully prepared and then speak to Miqol to trigger some more scenes, when you regain control you’ll be forced into a boss.
Boss: Sureny Telethia
The difficulty of this battle lies more in it’s preparation than it’s actual execution. If you’ve been relying on Shulk a lot and have gone into this battle with a Physical based party, then you’re going to struggle when it uses Soul Read however if you placed Melia as party lead with Mind Blast, you can negate it’s main threat. What’s more, you’ll only need to deplete 50% of it’s HP to conclude the battle.
Burst Animus - An Ether based Art that deals light damage to targets in a circle around it while inflicting Arts Seal, Bind and Knockback.
Ether Particles - An Ether based Art that deals massive damage to targets in a frontal arc while inflicting Ether Defence Down.
Killer Sky - An Ether based Art that deals massive damage to a single target while inflicting Topple and Knockback.
Killer Shot - An Ether based Art that deals light damage to a single target while also inflicting Chill, Ether Defence Down and Knockback.
Killer Tail - A Physical based Art that deals major damage to a single target while also inflicting Knockback.
Mega Ether Particles - Sunrey Telethia will use this once it’s HP drops below 70%, ending the battle.
Soul Read - Grants an Aura that prevents Physical attacks from landing.
As you can see from it’s list of Arts, Sunrey Telethia has many devastating Arts and due to the fact you only need to deplete 70% HP, you’ll want to go all out to avoid them as much as possible. Of special note is the Soul Read Art, this is where you’ll be hurting if you don’t have Melia’s Mind Blast Art or a fully Physical party. That aside, focus fire on Sunrey Telethia and you should have no problems, it won’t take long to reach that 50% mark to end the battle.
Many more scenes will take place following this battle as this short Chapter concludes, beginning the final Chapter.