Yu-Gi-Oh! Episode 162: "On the Wrong Track - Part 3"
King of Atlantis
At some point after Dartz was corrupted by the Orichalcos Stone, he was the one leading the Duel Monsters to battle against Dartz. Seemingly defeated, he, along with his granddaughter, Dartz' daughter Chris, and Skye, retreated to a remote location. Yami Yugi and Téa were found by them after the train they were on lost control.
When Yami Yugi had lost confidence in himself, after his Legendary Dragon Timaeus had abandoned him in his last duel, Ironheart said that he would hold on to it for the time being. He then asked what Téa and Yami Yugi were doing there, and they told him they were searching for a friend. He then decided to show them to the sacred spiritual ground, where he believed Yugi could be found.
When Yami Yugi entered the sacred ground, Téa at some point tried to follow him but was stopped by Ironheart, who informed her that only one person at a time could enter the area without angering the spirits. There do seem to be times when it is alright to anger the spirits though, as Ironheart entered the area when the Orichalcos Soldier summoned the Seal of Orichalcos against Yami Yugi. He rushed in, and tried to bring Timaeus back to Yami Yugi, but was struck down before reaching the seal. At that time, Chris caught up with Ironheart, and was ordered by him to bring the Legendary Dragon to the pharaoh.
After Dartz's defeat, he, Dartz, Chris, and Skye all disappear with Atlantis as it returned to the sea.