Sinister Squashling

The Sinister Squashling item summons and dismisses a Sinister Squashling companion.

Source
Sinister Squashling is a rare drop from the Headless Horseman. The Horseman is found in the Graveyard wing of Scarlet Monastery during the Hallow's End seasonal event. There is also a decent chance (purportely between 5 to 20%) of obtaining it from a Treat Bag or Crudely Wrapped Gift. The latter is obtained after you summon and defeat the Headless Horseman in your daily quest.

Trivia
The Sinister Squashling uses the same model as the Pumpkin Fiend.

Achievements
The Sinister Squashling is one of the items needed for.