In Longnotch, Aloy encounters Burgrend's daughter Varga, an Oseram tinkerer with a special interest in technologically-advanced ranged weapons. Among these is the weapon favored by the chieftain Aratak, the Banuk Icerail.
After receiving an Icerail at the end of the side quest For the Werak, Aloy can visit Varga who will be grateful to examine the weapon and ultimately declare it to be operating at half its potential. She offers to improve the weapon, but to do so she needs the mandible from a Thunderjaw.
Varga asks Aloy to meet her at the Thunderjaw machine site near the Valleymeet, just east of Dawn's Sentinel. After taking down the machine together, Varga will linger nearby. Aloy can speak to her then to improve the weapon or catch up with her later back in Longnotch.
- Meet Varga at the Thunderjaw Site
- Gather a Thunderjaw Mandible
- Return to Varga
- It is not necessary to meet Varga and dispatch this particular Thunderjaw to advance the objective. Looting any Thunderjaw after starting the quest will provide Aloy with a Thunderjaw mandible necessary to upgrade her weapon.