When Diva appeared in the same dimension Mani died in, he finds the Millennium Ring there. Without touching it, he gets engulfed in its evil. Diva is transformed by the ring into Dark Diva, which is fused with his chest. Diva then returns, and makes everyone at Kaiba Land except for Yugi and Kaiba disappear in a wave of darkness.
Yugi identifies him as Diva, but the latter states that "Diva" is no longer in control, rather, he has saved him from his fate. Kaiba and Yugi then agree to team up and Duel him. The Duel is a Shadow Game, where players' bodies fade away as they lose Life Points. Diva manages to defeat Kaiba, who hands Yugi the Millennium Puzzle, before disappearing. Towards the end, Yugi's body reaches its limits and he finds himself incapable of drawing his next card. Suddenly Atem appears, gaining control of Yugi's body. Atem draws and Summons "Palladium Oracle Mahad". Using "Mahad", he defeats Diva, whose body reverts to normal, before disappearing.
Dark Diva uses a "Cubic" Deck, which is largely focused on continuously Summoning and "leveling up" his "Cubic" monsters.
During his Duel against Yugi Muto and Seto Kaiba, he focuses his strategy on his most powerful monsters, his "Crimson Nova the Dark Cubic Lords", with the option of Fusion Summoning "Crimson Nova Trinity the Dark Cubic Lord", as well as dealing large amounts of effect damage to himself and his opponents.