The boss's attack priorities are listed on its sheet. It will, functionally speaking, always go after Jefuty. Put her in the middle of a flower field so that the boss has no choice but to step on the flowers to attack her, activate Emergency Dodge. Leaving her on flowers will also deactivate her extra turns. You have plenty of things that can inflict Grounded on someone as well, so you can always surround her with tripwires to try to force her onto flower tiles.

Later on, be prepared for her to lock Jefuty in place and charge up a line attack towards her. This instakills 2 things along that path and she'll stop at the second - place barries or turrets so that the second one she instakills leaves her standing on a flower field. You know when it's going to happen, so you can again place Jefuty in a position where her path will cross a flower field and you can catch her in it.

Once you know where she's going to be, prepare ahead of time with some turrets, RC bombs, whatever you like. She'll explode pretty quickly - boss fights in this game are a matter of reading exactly what the boss' priorities and skills do and once you've got the hang of it it's pretty chill.

Originally posted by Stelas:

The boss's attack priorities are listed on its sheet. It will, functionally speaking, always go after Jefuty. Put her in the middle of a flower field so that the boss has no choice but to step on the flowers to attack her, activate Emergency Dodge. Leaving her on flowers will also deactivate her extra turns. You have plenty of things that can inflict Grounded on someone as well, so you can always surround her with tripwires to try to force her onto flower tiles.

Later on, be prepared for her to lock Jefuty in place and charge up a line attack towards her. This instakills 2 things along that path and she'll stop at the second - place barries or turrets so that the second one she instakills leaves her standing on a flower field. You know when it's going to happen, so you can again place Jefuty in a position where her path will cross a flower field and you can catch her in it.

Once you know where she's going to be, prepare ahead of time with some turrets, RC bombs, whatever you like. She'll explode pretty quickly - boss fights in this game are a matter of reading exactly what the boss' priorities and skills do and once you've got the hang of it it's pretty chill.

I have no turrets left because I had to use them during the siege.

Save Mendo's SP and use it on his ultimate once the boss is vulnerable. This'll resurrect your turrets and let you recover them for immediate redeployment. Turrets are just extras, though, you can use barricades or anything else you like to block her charge attack, and Jefuty + Atena Mad Bombering should still provide a lot of damage.

The tactic is to place Jefuty on enemies red tile, so any adjacent blue tiles were on flowers (Boss specialy avoids them, so you have to make her no choice but to stand on those)

Another tactic is to use Athena's Taunt so that Lige charges her and ends on the flower field. You also don't need to use barriers or turrets. Scanners work for that as well. But also drop all RC bombs around the spot Lige ends up. So, after the flame grenade. You can have several RC blasts lowering her health drasticaly.

to me it was fun trying to use my brain and figure out how the hell to beat it with limited resources after a long siege, but i completely get the frustration and the design is so rage-inducing, there's so many points in the game where you feel like "oh my god am i going to have to restart this whole level over?"