Magical-MagicianGirl

The Dark Magician Girl is a rare card Yugi first used in the Battle City Tournament during his duel with Arcana (episode 62: The Master of Magicians Part III). The Dark Magician Girl has an attack power of 2000, which increases by 300 for every Dark Magician in the graveyard. She and Dark Magician are a formable tag-team, able to combine their powers for stronger attacks. Dark Magical Girl was also Tea's Deck Master during her duel with Crump of the Big Five.
It eventually turned out that Dark Magical Girl is the Ka (or Spirit) of Mana, an apprentice of Mahado, a priest of Pharaoh Atem who was the previous owner of the Millennium Ring. After Mahado died and became the Dark Magician, Mana promised herself that she would become a great magician, following after her teacher. When Mana died, her spirit then became the Black Magician Girl.

During the DOOM saga, Dark Magician brought Yugi and Yami to the World of Duel Monsters to revive the Sacred Dragon Timaeus to help them to fight DOOM. She did the same with Kaiba and Joey who gained the only two dragons, Critias and Helmos. Through the power of Timaeus, Dark Magician Girl becomes the DarkMagic Dragon Knight, who only attacks if Yugi discards a card from his deck.