After finishing Revenge of the Nora, War-Chief Sona will be in Mother’s Crown and have an errand for you. She has a few tasks for you to help with some defenses, the first of which is to retrieve some Chillwater for her. This resource is fairly common, as it drops from any machine that has Freeze Canisters or uses freeze attacks, such as Lancehorns, Glinthawks and Freeze Bellowbacks. If you somehow don’t happen to have any, which you probably would and will immediately hand them over, you can find some Lancehorns to the southwest of where Sona is located.

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There are some Lancehorns nearby for you to grab a Lens (left). The watchtower is high on a hill, so you’ll have to climb to reach it (right).

Once you hand over some Chillwater, she will present two more tasks for you, the first being to secure a Lancehorn Lens. Again, use the nearby site to kill and loot a Lens from one of their lifeless corpses. With that out of the way, you can concentrate on the other task, which is to deliver some Signal Arrows to Orn. If you’re still in Mother’s Crown, take the southern exit and go west at the first split, then south at the next one. Continue straight south, bypassing two more forks, and upon reaching one more fork, go southwest to find the watchtower with Orn. Climb up to it and deliver the arrows, then return to Mother’s Crown to find Sona has relocated to a watchtower. Climb to the top using the nearby footholds and speak with her to end the quest.