That was right. Ling Tian had urged the Demon Slayer Alliance cultivators to join their side for the Heaven Locking Pillars. With his discerning eye, he could easily tell that they were Natal Dan Artifacts, not much inferior to the Sky-Breaking Bow and the others. Even Ling Tian would need a very long time to refine Natal Dan Artifacts of this caliber, but he didn't have much time to spare for it. After all, he still needed to focus on improving his strength and breaking through to the Saint level.
Once Tu Tian and the others were killed, the Heaven Locking Pillars would become ownerless. In that case, Ling Tian and his companions could try to forcibly refine and subdue the Natal Dan Artifacts, but that too would take a very long time. And there was no guarantee they could kill Tu Tian and the others, since Tu Tian's group still had a chance of escaping the Heaven Sealing Grand Formation.
If that happened, Ling Tian and his companions would lose their chance to obtain the Heaven Locking Pillars. That was the last thing they wanted.
Moreover, a sect or cultivator possessing the Creation Divine Tree could charge into the Sacred Ruins Abyss at any moment. In that case, Ling Tian and his companions would have even less time to refine or subdue the Heaven Locking Pillars. The best solution was to have Tu Tian and the others join them, then work together to set up the formation.
This point of Ling Tian's was easy enough to use to persuade the Demon Slayer Alliance. After all, they all knew what Ling Tian and his companions truly wanted. More importantly, they also understood that, as Ling Tian had said, if Tu Tian and the others fell, the Heaven Locking Pillars would