Halo Infinite: Mythic skull location in Repository

Mythic skull is one of those Halo Infinite collectables that can only be looted during a mission so here is a quick guide on how not to miss it.

Halo Infinite is not allowing replaying missions for some reason so when a collectable is set in the mission instance, you have no choice but to loot it before going back out into the open world. This is the case with the Mythic skull that will increase the health of all enemies, should you decide to activate it during a new game. 

Mythic skull is looted during the Repository mission and the chamber that holds it is rather well hidden. You will need to progress the mission until you reach the solar walls. They are basically huge and yellow in a Forerunner structure so they are hard to miss but to know for sure, you can listen to the moment The Weapon tells Master Chief that "they will incinerate [him]" if he touches any of them.

Keep progressing and you will come up to a crossroads solar walls where the floating pillars are changing direction. 

343 Industries Halo Infinite - Note that the pillar next to the health bar is turning to its right

Follow the pillars and you will reach another curve in the pillars' path. This is when you will know you've arrived to the right place as the turning point for the pillar is where you will start climbing the walls, up a few platforms.

343 Industries Halo Infinite - This is the second turn for the pillar. Ignore it and grapple upstairs

As soon as you start grappling upwards, you will notice several platforms protruding from the walls. You can land on any of them if you need to get your bearings. From that point, just grapple to any platform you see and you will come across a Forerunner door that will open as you approach it.

343 Industries Halo Infinite - The Forerunner door opens to lead you through the final tunnel

Go through the door and the tunnel beyond. There is only one path there so just go through it and you will reach the skull.