While they hadn't reached the Divinity Transformation Stage, their strength had barely made it there; otherwise, Xu Mu wouldn't even have spared them a glance.
The reason for this was rather simple, they must have used some special method to temporarily enhance their strength. Given the foundations of the Cluster Stars Sect, this wasn't difficult to achieve.
Moreover, the two ambushing cultivators exuded a potent life force, making it easy to guess this.
It's easy to suspect the Cluster Stars Sect as well, because no one else in this vast sea could pull this off.
The two of them must have already reached the late stage of the Nascent Soul, otherwise, no matter how clever their method, it would have been impossible to attain this level of strength in such a short time.
Probably, they were nearing the end of their lifespan, which is why they were used as cannon fodder.
The objective was straightforward: to deplete the talismans on Xu Mu.