There are some people in the world of Horizon who desperately need to sell their Machine Hearts for water. Drakka is one such person. He needs your help to collect Machine Hearts from the nearby herd. There are too many dangerous machines for him to do it alone. This is how you complete the side quest Thirst for the Hunt in Horizon Forbidden West.
You get this quest by meeting Drakka in the Arrowhand. This small settlement lies just southwest of Scalding Spear and north of Campnowhere. Use the map above for reference if needed. After a short cutscene, you’ll need to track down Drakka if you choose to leave now or meet him later. After following Drakka or meeting him, you will get a cutscene.
When the cutscene is over, climb the rock wall and get ready to kill some machines. You will need to kill a few Ravagers before you can kill the Fanghorns. Be on your guard during the battle. Once finished, collect all the Machine Hearts. Now Drakka wants you to help him at the Thunderjaw Site.
Follow Drakka to Thunderjaw Site. You will need to fight a group of Burrowers first. Then Thunderjaw will reappear. Thunderjaws are hard to beat. They have a lot of firepower. Make sure to aim the weapons all over Thunderjaw’s body to deal a lot of damage and prevent it from dealing too much damage. After the battle, check on Drakka and he will comfort an injured warrior. Return to Arrowhand with Machine Hearts to complete the quest.
https://www.gamepur.com/guides/how-to-complete-the-thirst-for-the-hunt-side-quest-in-horizon-forbidden-west How to complete the side quest Thirst for the Hunt in Horizon Forbidden West