Yu-Gi-Oh! Episode 72: Unite!
Episode 72 of 224 of Yu-Gi-Oh!, aired September 11, 2001, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Yugi and Kaiba start to exhibit signs of teamwork, but it's too little too late to stop Umbra and Lumis summoning their Masked Beast Des Gardius, a monstrous menace even more powerful than the Blue Eyes White Dragon.