The Pumpkin Spectre Polymorph is a seasonally exclusive polymorph for The Elder Scrolls Online available through the Crown Store. It can only be purchased during the Halloween season in October, and is not available for the remainder of the year. It allows the Vestige take on the appearance of a pumpkin headed spectral figure.
"Speaking of the Witches' Festival, that's when the hedge wizards summon the vision of the Pumpkin Spectre, a horrific figure that looks like it stepped out of a skooma-induced nightmare! And with this costume, the wearer can take on the semblance of these dread monsters."