You will need to learn “eye of the Beholder” spell and find three places on the map.  
First is gigantic statue’s head in the naga’s area. 
Second is the statue over waterfalls near Iss’ house. 
The third is an altar in the Mother Sabrina’s  Monastery.

The quest also opens option to help in the monastery. 
Improves relationships with Sabrina and has 3 variants 
of short reactions from the nuns at the moment. 
I n the future it will be triggering some more interesting events.
Agatha can’t be summoned second time at the moment, 
but I’m planning her to be reappearing character in the future.