The battle between the three was not divided into teams, but a two-on-one situation could emerge at any moment. Within the two-on-one dynamic, reversals were just as likely; one second they were allies, the next they might turn their weapons on each other.
When he first started training, Xin Yun found it very difficult to adapt. Since he had little attacking ability, his acid spray was difficult to aim and even if it did hit, the damage was minimal. As for Thunderbolt, it consumed too much energy, and Xin Yun didn't want to rely on it. Otherwise, his strength would hardly improve.
The power of Thunderbolt was indeed formidable, especially in such an enclosed space. Once paralyzed, the likely outcome was crashing into the stalagmites. For the three of them at present, Thunderbolt was simply an unsolvable threat; once unleashed, someone was bound to meet with misfortune, whether by hitting a pillar or falling to the ground—none would be spared.