The Shaman's Mask is an item gained by defeating 12 colossi on Hard Time Attack. It reduces the damage colossi do to Wander, but it has no effect on the damage he deals to them. It is the same mask that Lord Emon wears and goes along with the Shaman's Cloak and white Agro.
Dormin says the following upon retrieving the item:
|“|| That is the 'Shaman's Mask'...|
By wearing it, thou shalt receive fewer injuries...
- If Wander wears the Shaman's Mask during the fight with Pelagia, Lord Emon will not be wearing his mask during the cutscene following the colossus' defeat. Wearing the Shaman's Cloak, however, does not affect the cutscene.