In the cave. Xionmao explained to Lifen and Ming.
"That blue stone you're talking about could be Kreg. It gives strength to someone weak and makes a person active. Other humans gained temporary powers while using it but this seldom happens. During wars in the past, the other guardians gave this stone to physicians to sustain the life of their patients and to give them the strength to continue healing the wounded.
"While village warriors used the stone to defend their people, some Chiangdas found it and used it for their own evil motives and caused chaos. Maybe, these men got them from those who had it before.
"If that man has blue stones as big as those, you better be careful. Even if you're a Chiangda, you must avoid direct confrontation. Most of all, the birds saw Chiangdas helping the Goding army. So, there's a big possibility that man could be a Chiangda too."