Scarecrow Spectre Mask is a helm in Elder Scrolls Online.
How to get Scarecrow Spectre Mask
You must complete the quest The Witche's Bargain and use the buff from the Witchmothere's Whistle to transform into an undead. This can only be done during The Witches Festival.
Once you are undead, defeat any world bosses, delve and group dungeon / trial bosses, or dolment bosses to obtain Plunder Skulls. The mask drops randomly from them.