The titular ability of Nightmare is his ability to seem in dreams, possibly prior to the target had encountered him in the flesh inside of a form of sick omen or within the minds of survivors following a terrifying assault. He can shift into the astral and ethereal planes. https://moodjhomedia.com/story2958572/how-much-you-need-to-expect-you-ll-pay-for-a-good-nightmare-mu-online-season-20