Once Shadow Rifts are open, Fused Shadelings are the most efficient way of farming Pure Horror, dropping 3-4 each. Ink Blights drop a smaller amount of Pure Horror as well, but cannot be killed as often. The Resting Horror also drops 1 Pure Horror if Shadow Rifts have been activated.
Pure Horror is used to craft the Dreadstone Helm and Dreadstone Armor, as well as the Shadowcraft Plinth and all of the items craftable at said station in the Shadowcrafting Filter. It can also refuel anything fueled by Nightmare Fuel at twice the efficiency. For example, the durability of Bone Armor is restored by 50% per Pure Horror, rather than the usual 25% per Nightmare Fuel.
Wilson with the Shadow Courtier Skill can craft 2 Pure Horror with 1 Dreadstone, as well as use 3 Pure Horror to craft 1 Dreadstone, or use 1 Pure Horror to craft 2 Nightmare Fuel.
Attention: The following categories are only for the players look up the page based on their first impression, they have nothing to do with the actual categories/behavior/function/tags of these items