Il nido di zeugl, or nest, is the scene last "mostro boss" battle. It takes place in a part of the fogne in the Quartiere del Tempio which was previously inaccessible. The entrance to this area is found by going through the door immediately east of la bottega del fabbro nanico in il distretto dei non-umani and then descending to the cellar.
The door is locked for the duration of the game. The key to unlock it is obtained only during the Epilogo from a wounded Order soldier lying in the street, or from Triss.