Storm King's Thunder
An outcast giant that took up residence in an abandoned old tower, Humbaba's life was forever changed when he discovered a nifty hat. When he put it on, he was possessed by the spirit of a powerful warlock who had stored his essence in a cursed item. Gathering a small army of goblins, hobgoblins, ogres, and gnolls Humbaba was well on his way to cementing his power in the North when he stumbled into a fight against the adventurers.
Incapacitating the giant, they were able to remove the headband and free him from the possession. The giant was grateful, promising to protect Parnast until the heroes could return.