Umbrals are a type of infernal that occupies a distinct niche in the Outer Abyss, benefitting from being able to slip into Caen more easily than others. They possess a special connection to shadows that lets them exploit darkness to serve as gateways. Guardians are often contracted to bind into the shadows of important infernal assets, lurking unseen to await the time they are needed, at which point they spring into action in defense of their charge.