One of the four Red Skulls in the Ghost Village
The Red Skulls are part of the side quest Remains of the Damned given to the Hero by Mongina in the Jungle.
There are four Red Skulls found in the entire game, all of which are located in the Ghost Village. Once all four skulls have been brought back to Mongina and the quest is completed, she rewards the Hero with a Cruel Cudgel.