Not everyone deserves it
The third elder's target was Kora. He remembered Aru calling him his master and decided to exact revenge by attacking him.
Some might think it was an impulsive decision made by the third elder in the heat of the battle.
But that was not the case.
After realising that he couldn't beat Aru, the thought had been circulating in his mind for a few minutes. And to execute the plan, he waited for the opportunity.
So, when Aru stopped and asked if he was willing to stop, the third elder got the chance he was waiting for.
He immediately made an ice wall to block Aru from interfering and dashed at Kora.
He could see the previous clan leader, Paru sitting next to Kora and he knew of the relationship between them.