Etinṣib Ziwa only appears in a few chapters of the Mandaean Book of John.
Nbaṭ then calls the 21 sons of Yushamin, led by Gubran, to fight against Etinṣib Ziwa.
On the first three attempts, Gubran was able to catch the arrows with his right hand, but on the fourth shot, an arrow struck the forelimb of Paraheil, Gubran's vehicle who is a heavenly steed or warhorse.
This provokes an all-out war in which Yawar, Bihram, and Yukabar slaughter all the sons of Yushamin.
[1] According to Chapter 3 of the Mandaean Book of John, Bihrath-Anana is the mother of Etinṣib Ziwa.