From DownSights: “In this guide we will show you how to find all 16 of the new limited-time exclusive rewards in The Haunting of Verdansk Trick or Treat Scavenger Hunt. With this mid-season Halloween event, 16 rewards are scattered in each major part of the Verdansk map. The rewards include charms, weapon blueprints, calling cards, emblems, and sprays.”
Source: N4G PC The Haunting of Verdansk – Trick or Treat Scavenger Hunt Guide