Sivan was shocked when he heard the description of the undead creatures.
It could be said that he has a fair knowledge of the undead creatures from Sam's memories. And in fact, he can find some similarities to the undead creatures from those memories.
But he cannot exactly figure out what these undead creatures are. What kind of creatures they are? How advanced they are in the undead hierarchy. He cannot identify that.
And if there is only one kind of new undead creature, he would have been able to swallow it. But the descriptions he got are extremely confusing and terrifying.
"An undead creature was being hit by a soldier constantly, but it is constantly emitting black smoke which consumed the soldier who is currently crazy and seemed to be in intense pain.
He is acting as if he is hallucinating and attacking the same team members.
