I've had this concept since we first heard about the skull warriors, and have finally gotten around to putting it into action.
Sorry for the crap quality; I still haven't gotten a new camera charger.
And yes, it can shoot.
Story: Kaitapah was a warrior that lived back before the great cataclysm. He was something of a pariah; not coming near society unless absolutely necessary. Even when he did, he carried a strange, uneasy aura about him. It was as though the shadows clung to him, haunting him and whoever he came in contact with. Even more frighteningly, someone from the towns he visited would go missing every time he showed up. Often it was a child, elder, or sickly person; someone who wouldn't be able to fight back if abducted.
As it would turn out, Kaitapah was indeed kidnapping and torturing villagers. This was discovered when the Protector of Jungle's son was taken and Kaitapah had been in town around that time. Ekimu counseled with the protector and an island-wide search went underway, the warrior's dwelling being one of the first stops.
Behind the hut's 5 meter tall walls, there was a sight more gruesome than anyone had anticipated. Parts and guts littered the yard, as well as a multitude of severed heads. Kaitapah had not only taken more than 18 victims, but had removed their heads with a scythe, put them on stakes, and clamped their mouths shut. He was feeding off their life force via a type of deranged dark ritual.
Makuta, who came along in case his brother and PoJ ended up over their heads, was shocked by the carnage and flew into a rage. The mask maker disarmed and bludgeoned Kaitapah, before pulverizing his body until only a few bones remained intact. He then lit the dwelling ablaze with a pouch of fire essence that he had carried in case the quest went awry. The experience seemed to have a notable effect on Makuta, who thereafter began to push for he and his brother to rule the island much more stringently.
Kaitapah, however, was not gone for good. A few years after the cataclysm, Kulta ran across the murderer's scorched grave. Sensing that the reaper's oppressive presence still lingered, The Skull Grinder reanimated the remains, along with a bit of the razed earth around them to behold Kaitapah in all his maddened might.
The newly reborn Skull Reaper forged and alliance of sorts with Kulta and has since aided the Skull Grinder in his endeavors. The Toa have been fortunate enough not to run across Kaitapah yet, though he still lurks somewhere in the ancient city.