the ZI was trained then, because these pop very far away from the ZI. Usually in the area on the west side of the river down below the cliff or inside that tunnel (if not always inside tunnel)
Reguardless, it wasn't where it belonged and isn't something to normally worry about.
They are Shadowknights and cast the usual SK spells including a Harm Touch for 1000 or so. They melee for 600s but have low MR and are easy once slowed.