Yu-Gi-Oh! Episode 178: "A Duel with Dartz - Part 2"
Queen of Atlantis
Dartz became king of Atlantis around the time the Orichalcos arrived in the city. A few years after its appearance, people started turning into monsters. Dartz believed this was the Orichalcos showing the true colors of wicked people. Iona began to transform into such a monster and ran when approached by Dartz. Dartz ran after her, but the time he caught up, she'd completely transformed into a monster. She is seen dropping a body when Dartz approaches her (the body is removed in the dub). She proceeds to attack Dartz, but he strikes her with his sword, killing her (this is also removed from the dub).