My idea for some d&d baddies who are to the shadowfell what star spawn are to the normal world. If magic is on a scale from 1-10, they are on the negative. As such, they have incredibly powerful resistance (or even immunity) to magical attacks. They use their third eye to sense wizards, warlocks, and sorcerers from incredibly far away and hunt them singlemindedly. They never speak, and the closest to communication is a horrible, ear-splitting screaming heard by arcane power users when in their presence. Whenever the magical black hole known as “The Great Void” draws near the shadowfell, these beings are spontaneously generated and make their way into the real world.
More coming later when I get my old sketchbook to a place where I can scan them.