The Magic is involved with Kain's voodoo doll, Mr. Cursey. After anyone places a hair on the doll, if someone manipulates the doll, the "victim" is manipulated in the same manner. When a person isn't holding the doll, the person who the doll is attuned to is able to move normally.However, a second aspect of this Magic is that Kain can magically alter the doll's properties, allowing him to change the properties of the person attuned to the doll in the same manner.For example, by turning his doll into iron, Kain can do the same with his own body. Other forms of Magic can be used in conjunction with this Lost Magic, for example when Natsu lit the right hand of the doll on fire, this was reflected on Lucy, who was under the influence on the doll, without actually damaging her body.