Its cries sound like incantations. Those hearing it are tormented by headaches and hallucinations.
Mismagius is a purple, ghost-like Pokémon. It has a round head with elaborate tufts resembling a witch's hat atop it. The tips of the tufts are paler than most of the body. It has a thin, red mouth that resembles the letter "W." Below its head, Mismagius has a long neck with a round lump midway down. Three, elliptical red spheres surround the upper portion of Mismagius's body. There are extensions on the sides of its lower body with the foremost ones tattered compared to rear ones. This gives Mismagius the appearance of wearing some kind of cloak.
If it is powerful enough, Mismagius can use advanced incantations for various purposes, such as causing misery or happiness. People that hear its cries will usually receive headaches and hallucinations. As shown in the anime, Mismagius can put its victims to sleep, and cause them to enter a strange dream world without their noticing. If Mismagius falls asleep or is knocked out, the victim will wake up.