Lu Li had completely offended the Ji Mengtian, Yang Xuan, Die Feiyu, Lu Ni and Lu Suan. There was a chance that Die Feiyu wouldn't get back at Lu Li. On the other hand, if the five were kept alive, Ji Mengtian, Lu Suan and Yang Xuan would definitely seek revenge.
The thing was, if Lu Li did kill the five, the four forces they were from would drown the Northern Desert in blood. This was a conundrum for Lu Li.
Lu Li thought that he could make a bigger deal and bargain with the four forces with Ji Mengtian's and the other's lives and the authority of the Demon-slaying Hall. He could negotiate for terms for his benefit so that the four forces wouldn't have the courage to get back at him.
It was a nice idea!
But reality was cruel. Jiang Qiling was taken away right after they came out. The only leverage Lu Li had was taken away from him as well. Ji Mengtian and the others were saved and Lu Li no longer had the Ding of Barbarian God.