The Fairy as she is called, is a magical and angry fairy who is the main antagonist in the W.I.T.C.H. Halloween Special Issue and one of many villains in the W.I.T.C.H. universe.
During Lillian's trick-or-treating, she and Cornelia stop at the last house to get some candy, but the girl who lives there hates Halloween and drives them away from her home.
After that she follows the siblings into the mysterious forest, and sees the Laughing Tree and Cornelia touching the Pumpkin Heart. There she realizes that the pumpkin was the heart of the Halloween nightmares.
She decides to take away the heart and bring it inside her house to eliminate the nightmares, thus ending the existence of Halloween.
The Pumpkin Prince detected that someone stole their heart and together with the other nightmares they roam the city with the hopes of finding the Pumpkin Heart. After a brief explanation, the nightmares and the Guardians figure out who was behind the stolen heart through Cornelia.
They confronted the Fairy who declared that she was intending to erase Halloween forever. She and the Guardians fight, and she is very powerful and seemingly invincible. She stabs the Pumpkin Heart, injuring all of the nightmares. Later she was approaches Lillian she finds a Halloween box and is frightened by it. The girls realize her weakness and defeat her by disarming her of her magic wand.
Abilities and WeaknessesWhile the Fairy is not as powerful as the Guardians, she seems to have mastered the art of transfiguration/glamour. She transforms the girls' magical attacks into girly ornaments and even colors their outfits pink.
Her magic comes from her wand. The girls discover that fear is her weakness, and decide to imitate her techniques by transforming themselves into monsters.
It is then revealed that she is a small humanoid much like a pixie, and the girls destroy her weapon so that she will become harmless.