Weighted Jack-o'-Lantern is a common drop from Headless Horseman. The horseman is found in the graveyard wing of Scarlet Monastery during the Hallow's End seasonal event. It is also found in the [Crudely Wrapped Gift] (was formerly found in [Smashed Pumpkin Loot]). It is also given as a reward for the fire fighting daily quest during Hallow's End.