That's a bit rough. Seing solo videos from Mione you can clearly see that the boss is being pushed back into Twilight realm on P3 somehow, while Mione is actually alone. Also, it is already set to mend if either side does not DPS. The values i put was to ensure that not any side would still go AFK or have only one guy DPS Halion down (It's a boy, btw) while the other side tries to catch up.