The Lilliad demons appeared to as gray-skinned demons. Although they could produce human speech, they appeared to have no visible mouth. They were bipedal and moved very much like humans.
They were adept at using magic. At their full peak, a small group was capable of breaking a powerful protective spell cast by the Furies. Their power was linked to the lunar cycle, apparently being stronger at the full moon.
Lilliad demons were vulnerable against fire. It is unknown if they have other vulnerabilities.