Kratos can find many surprises while traveling the nine realms in God of War Ragnarök. You can find one rather large surprise behind an elven door in the Forbidden Sands of Alfheim. You'll need to find two keys to open it and complete the Desert Door Favor. Here is how to find the two keys for the door in The Forbidden Sands in God of War Ragnarök.
How to complete the Desert Door Favor in God of War Ragnarök - Alfheim
After finding a freeing the Hafgufa in the Song of the Sands Favor in the Burrows, you'll be able to travel to the large desert door located on a platform where the Map is circled above. To reach the platform you'll need to go on the platform's south-western side and find the barrier pictured below.
To break through it, turn around and grapple onto the stature behind you using X. The camera should pan around and prompt you to press X again to break through the barrier. Once you break through, you'll have several light elf enemies to fight before investigating anything on the platform. When you're finished fighting, check out the large elven door that Freya takes note of after the fight. It needs two keys to open.
Where to find the first key half in The Forbidden Sands in God of War Ragnarök
The first key is nearby the entrance to The Forbidden Sands. You can pick it up by interacting with the bright glowing spot inside the purple sand circle. The sand circle is located approximately here on the map.
Where to find the second key half in The Forbidden Sands in God of War Ragnarök
The second key is in the southwestern part of The Forbidden Sands. It's nearby a Nornir Chest that you may want to unlock while you are here. You can pick up the second key by interacting with the bright glowing spot inside the purple sand circle. The sand circle is located approximately here on the map.
How to beat Gravel Belly in God of War Ragnarök
Take the keys back to the door and unlock them to be greeted by Gravel Belly, a powerful boss. Defeat it and gather its loot: the Alfheim's Fortune Amulet Enchantment, a Dragon Claw, used to make Dragon Scaled Armor, Skirnir's Gambanteinn, a unique resource, and two Dragon Teeth. There is nothing else behind the door, so this boss' loot is your reward.
While you're here in Alfheim, you might want to complete the Elven Sanctum Favor in God of War Ragnarök. Check out How to complete The Elven Sanctum Favor in God of War Ragnarök and How to beat The Maven in The Elven Sanctuam in God of War Ragnarök here at Pro Game Guides.