Dark Storm could not be interrupted. It would last until players reduced Nunnally's HP to lower than 200,000, so passing this segment relied heavily on the healers. They could not simply heal, because this time they also had to predict when to heal. Only then could they fully nullify the disadvantages from the delay in healing times.
This segment also demanded a lot from the DPS. If they dealt damage quickly, they would be able to take a load of the healers' shoulders. If they were slow about it, and the healers ran out of mana, all that awaited them then was disaster.
Li Yi activated two powerful skills, Violent Bear's Protection and Rapid Shooting. His DPS immediately shot through the roof.
The party's two healers took turns healing and found that they were more than capable of managing this situation. Li Yi and the sisters also performed well with the DPS, and the Dark Storm vanished after a mere dozen seconds or so.