Magicked Skull  

You can also get the skull at shakrami maze in tahrongi canyon and there are also places in bururimi place where ghouls spawns (I know for sure there's one east Maurha's entrance) between 22-4

You need this for the sub job quest. It can be found in the valkurhm dunes between 21:00 - 3:00 from the ghouls that wander theplace at night.

You can also get it from the mines in the highlands if you happen to have someone in their 30's willing to back you up.