Black Magic is for attacks that gather their power from mazoku, or demons (who will be explained in a later episode). They are spell attacks that the mazoku themselves use. The Dragon Slave, being the most powerful spell in Black Magic, gathers its power from and is the spell used by the most powerful mazoku, Ruby-Eye Shabranigdo.

Lina specializes in Black Magic, so she has the ability to cast its most powerful spell. Most other characters in Slayers cannot use this spell.