Voices from the deepest part of the forest have offered you strange powers in exchange for your prayers. Congratulations! You are now a weird, chanting cultist! But, you have to look the part, so what kind of skull are you going to wear as a mask/headdress?
(I just started thinking about this when I randomly remembered the first time I met a goat and looked into its inhuman eyes. You can never really forget the look in a goat's eyes...)