Riselia is the girl who unwittingly undid the seal on Leonis's mausoleum and nearly died protecting him from a Void; left with no choice, Leonis "heals" Riselia with the only spell he is certain would work, the tenth-order spell "Create Elder Undead", a spell that worked so successfully on Riselia that she returned to life as the strongest undead being, a Vampire Queen.

(Source: Wikipedia)