This chapter contains a complete walkthrough for the mission Healer's Oath. Here you will find advice that will help you to complete this quest in the best way possible.
Beginning the quest
The mission will appear in the journal after you speak to Abas in the Sunfall. You will learn that his sister is sick but the healer can't help her. Aloy will decide to bring someone that can help her.
Course of the quest
In first order you must go to the Blazon Arch village located south. There you must find a man named Ghaliv. Follow he marked and you will find him near the lake. The conversation will reveal that he doesn't want to help the refugees.
After Aloy will push him, he will agree to help Abas' sister. However, he will have one condition - you must deliver him a Thunderjaw Heart. If you don't have the item, you must go the lair of the machine and defeat one. Before doing that you should start the Hunter Lodge plot in the Meridian as both quests are intertwined.
Once you have the item, Ghaliv will tell you to go to Meridian. There you must speak to Abas. This will trigger a short cutscene. After it the quest will end and you will gain the reward.