This weapon has two attacks. The first attack is "vaporize": it raises zombies in the air with a similar effect of the Storm Bow. The second attack is "mesmerize": it freezes zombies and Thrashers completely in place. While being held, any zombie or Spider within the skull's field of view will stand still until the player either puts it away or uses an attack. Note that zombies can still attack from behind the player. The skull is also required for the Seeds of Doubt easter egg, as the mesmerize feature reveals hidden rooms & objects throughout the map.
Take one of the four "uncleansed" skulls to its respective pedestal (the symbol on the forehead will correspond to a certain pedestal in the map) and prevent it from breaking while it is being "cleansed". There is one pedestal in the starting area, one in the Propeller Trap area, one inside the bunker, underneath the test subjects room and one at the docks. Zombies will appear out of green holes out of the ground and attack the skull, similar to when a generator is activated in Origins and Templar Zombies spawn to stop the player. If the zombies break the skull, the skull will be lost until the next round. Should the player prevent the attacks, the zombies despawn including Spiders and Thrashers and the skull must be taken back to its respective place in the Altar site. This is repeated until all four skulls are cleansed.
When all skulls are put back into their places, the debris by two of the pillars will be cleared and the player can enter the room to start the skull ritual.
During the ritual, Keepers will spawn and try to attack the player. The player must kill these Keepers and charge the skull.
When the ritual is complete, and the skull is charged, any player who wishes to obtain it can grab the Skull by holding the use button. Doing so will unlock the achievement/trophy "The Ultimate Sacrifice".
Inside the area the Skull of Nan Sapwe can be obtained, the player can reveal secret storyline information about the Keepers using the mesmerize attack. Doing so will prevent the Skull of Nan Sapwe's ammunition from reducing without using it.