His Alchemic Stars of Mortal Spirituality were a set of optical abilities obtained naturally from his comprehension of the Alchemic Dao. It was proof of his status as a Mortal Sovereign Alchemist, and was akin to Intent. It linked deeply with the Alchemic Dao and Mortal Dao, initially allowing him to perceive the Alchemic Spirit Remnants within others bodies.
He didn't know all of its abilities, but now he did. He could see what Eden always saw, and how he observed the world. This couldn't be reflected by spiritual sense. So when the world started to morph, he finally saw the truth.
The mana of this world had been siphoned away, and all of this mana had entered Su Mei's body. He tried to move, but every step was like trudging through dense mud. All the powers within his body were either halted or focused elsewhere. Kratos seemed to be allowing his body to move, focusing purely on preventing a strange force from infecting him.