Considering it was a close run thing with our side even more depleted than this, I think we will be fine with a neutral battlefield, unless there are more tricks to come. Potions (per previously) in mouths at let's get started.
Yulia is held up by a (one) vine, if we can sever that she will be back in the fight. Goma has the relevant dagger, so not sure how helpful that is. Maple could try putting a shot through it, but it may be more important to keep the pressure on Alide. Yulia may just need to hang in there (pun intended), drinking health potions in excess may allow her to fight to some extent. She is supposed to have the halo so even in a mistake we have insurance, although I would really rather not use it.
Otherwise much the same as the previous plan seems good. Sally and Beck can add in some close up granades. Dhalia has pressure and ice rain, so use that if it can avoid friendly fire.
In more detail:
Cure potions in mouths (swallowed as appropriate) everyone has an excess so use them freely.
Yulia, spam potions as required, but if the health drain is too much you should stop trying to fight. If you can fight, start with undermine (if it isn't just overridden by pressure), then blizzard, then cycle through the offencive spells, cure other people as required. That said, undermine might not work because status immunity. Using Open to strip her could also be intresting, but probably no more than a distraction given she seems to summon most of her tools.
Cherchiel, ball mode and charge. Don't leave her with time to do anything. Use weapons as needed.
Goma, puppet her, use the horn, then see if you and your knife can be any use to Yulia. You can also try puppet with different commands, anything to disrupt her.
Isalia, life drain and plasma rifle when you can. But I want you on spare potion duty, I don't want to bet on everything going perfectly so if anyone needs a potion and can't self administer your job is to help them.
Lri, go invisible of course. Use the plasma rifle at an opportune moment.
Lemiel, you have the rifle, blades, and angelic rays. Heavenly soothing as an extra backup cure.
Maple, plasma rifle and rail gun, with the targeting helmet. Shoot her (obviously), but you can also try shooting the vine (or the bulb) holding up Yulia.
Sally, charge in there similar to Cherchiel, but you have the neddel mace (hopefully it works) and close in grenades.
Talwa, magic armour, then rotate through the fire spells. Use potions as required to keep your mana up ect.
Beck, same as Sally, close range grenades.
Dhalia, pressure and ice rain. Shame we don't have a large undead army to take advantage of those stacks of mana, maybe we can take advantage of that if we do meet Moragana.