Gralens in the Emergency Shelter requests your help in defeating a Stone Talus in Akkala.
Quest Location
To start this quest, talk to Gralens in the Emergency Shelter in Lookout Landing after you have completed two of the "Bring Peace to...!" quests. Then talk to him again and ask about large monsters, and ask about the Stone Talus.
How to Complete the Quest
Go to the quest destination on the map, and the Stone Talus will rise up from the pond. Use Ascend to easily get on top of the Stone Talus, where you can try to walk onto the ore deposit on its back. Hit the ore deposit to deal damage. The Talus will knock you off after a while (or you can jump to safety first). If you are on the ground, keep moving and keep your distance to avoid getting hit by the Talus's arms. If the Talus has lost both arms, it will briefly put its body on the ground to create new arms, giving you a brief opportunity to hit its ore deposit without getting attacked.
After you defeat it, it drops a Talus Heart, which you can fuse to a weapon.
Talk to Gralens in the Emergency Shelter in Lookout Landing and tell him "I hunted something" to complete the quest.
Quest Reward
Gralens gives you 100 rupees. If you have also completed WANTED: Hinox and WANTED: Molduga, Gralens also gives you 300 rupees.