Dripping Blood and The Axe Kick

At the start, Re'Fua and Re'Gra were defending against the attacks of the Poltergeist that the Water Cage was unable to handle. And, using their Magic Artifacts, they were damaging the attacking objects little by little, wearing down their opponent.

If they kept up with it, soon after, the Poltergeist would lose any means of launching an attack, hopefully.

Once the Chimera Ras breached the Water Cage, the external damage it faced had become relatively less. And soon after, Re'Kha was able to mend the damage. And, it seemed she was able to defend against the attacks of the Poltergeist to an extent. So, only Re'Gra remained behind to continue damaging it while Re'Fua headed to help Re'Rel.

After all, the Chimera Ras was strong, too strong to face alone. If Re'Rel had as much Water Qi as their father or mother, they wouldn't have been concerned since Re'Rel would be able to spam strong Pranic Arts in succession and kill his foe.