The boss is just annoying to deal with. It's very random in how it attacks, especially with its AOE attacks on the second phase. I did not record my faster run, unfortunately.
*Credit to Rex Melynas for the thumbnail. Thank you!!
Weapon: Tisah Stalward Sword +80
Armor: Octo Armor +80 (x3) (L1 Performa, L1 Guard, L2 Enthusia)
Augments: BiS more or less.
BGM: Phantasy Star Online 2 OST Mid-boss