Yu - Gi - Oh ! - Episode 045 " Legendary Heroes , Part 3 " , known as " DM Quest 3 : Master of Dragon Knight " in the Japanese version , is the 45th episode of the " Yu - Gi - Oh ! " second series anime . It is the final episode of the Legendary Heroes arc . It first aired in Japan on March 6 , 2001 and in the United States on October 26 , 2002 . Plot Summary . While Tristan and Tea are still warding off the Big 5 ' s thugs , the flying machine has just been repaired , and Yugi , Joey , and Mai are set for the " Castle of Dark Illusions " . But when they approach the castle , a herd of monsters is waiting for them , and they defeat as many as possible while penetrating the barrier surrounding the castle . In the process , Adena ' s aide ( Earu ) takes a hit for the heroes , and his death angers Yugi so much as to call Yami into the fight from this point on . Although the flying machine is destroyed soon after , the heroes ride " Winged Dragon " and make it to the castle , where they must battle even more monsters . Meanwhile , the captured Mokuba is brought to join Kaiba in being sacrificed . However , Mokuba still has Kaiba ' s cards , and he uses " Swordstalker " to free Kaiba . Mokuba then hands Kaiba back his Deck and he then uses it to wipe out the monsters guarding him . Then , he and Mokuba rejoin Yami , Joey and Mai . Suddenly , the Big 5 ' s voices are heard . Having monitored the progress of the heroes , they have decided to join the battle personally . By overriding the game , they brush away the castle setting . Then , they skip any need for a sacrifice ritual and summon the " Mythic Dragon " immediately , speaking through the monster . For good measure , they set a condition that only Dragon - type monsters are allowed to attack . The heroes ' initial attacks are useless , and the Big 5 take advantage of Mokuba ' s lack of a monster to target him . Joey orders " Red - Eyes Black Dragon " to take the attack instead , and when his Life Points reach zero , he vanishes . Mai also falls by intercepting the attention of the Big 5 while Yami Yugi tries to convince Kaiba that he has a plan but needs Kaiba ' s help for it . But the next attack targets Kaiba , and Mokuba pushes him out of the way , collapsing fading from his brother ' s arms . This convinces Kaiba to cooperate , and Yami Yugi summons " Dragon Master Knight " to defeat the dragon . In a rush , he and Kaiba reappear at Adena ' s palace , and she honors their bravery by showing that she is in fact the " Mystical Elf " . With her magic , she brings back Key Mace and their friends , and the heroes return to the real world safe and sound . Featured Duels . Yugi Muto , Joey Wheeler , Mai Valentine , and Seto Kaiba vs . The Big Five . Epilogue . Yugi and Kaiba are transported back to the castle of Princess Adena . Despite the citizens and the princess thanking them for saving them , Kaiba and Yugi are still distraught that they lost their friends and loved ones back in the battle . Adena transforms into the " Mystical Elf " and uses a spell to revive Joey , Mai , Mokuba , and Earu . The gang go back to their world just as Kemo and his thugs break down the doors to the virtual pods . Featured cards . The following cards appeared in this episode . Cards in italics debuted here .