Yu - Gi - Oh ! - Episode 050 " The Mystery Duelist , Part 1 " , known as " Challenge from the Past - The Terrifying Zera " in the Japanese version , is the fiftieth episode of the " Yu - Gi - Oh ! " anime . It is the season 2 premiere , as well as the first episode in the Battle City arc . It first aired in Japan on April 10 , 2001 , and in the United States on November 16 , 2002 . Summary . Yugi Muto now has exchanged the brown rope for a chain in order to keep his Millennium Puzzle as safe as possible . Yami Yugi explains that this change is vital since the Millennium Puzzle connects the two , and he also senses that fate has more in store . Then Yugi and Téa Gardner are heading to the soccer game at school when they come across a fortune teller who Yugi believes can help him see what is in the future for him . The fortune teller asks for a personal item and suggest the Millennium Puzzle which , once in hand , he steals it . Téa runs into Yami Bakura , who wants the Millennium Puzzle , and uses his Millennium Ring to find the Millennium Puzzle . The fortune teller then alarms Yugi by saying that the only way to get the puzzle is to win it in a Duel . But the catch is , since the Millennium Puzzle isn ’ t close or on Yugi , then he would have to do this Duel without Yami Yugi ' s help . During the Duel , Yugi realizes that only one person has a lot of machine cards , and that is Bandit Keith . His guess is right , but it is not truly Keith since he is now the host of someone else — Marik Ishtar . Meanwhile , Téa , Joey Wheeler , and Tristan Taylor search for Yugi . Featured Duel : Yugi Muto vs . " Bandit " Keith Howard . Turn 1 : Yugi Yugi draws . He then Normal Summon s " Celtic Guardian " ( 1400 / 1200 ) in Attack Position . Turn 2 : Keith Keith draws . He then Set s a monster . Turn 3 : Yugi Yugi draws . " Celtic Guardian " attack s and destroys Keith ' s Set monster , " Cyber Jar " ( 900 / 900 ) . The Flip effect of " Cyber Jar " activates , destroying every monster on the field . After that happens , the Flip Effect of " Cyber Jar " lets both Yugi and Keith excavate the top five cards from their respective decks and Special Summon any Level 4 or lower monsters them drew in Attack Position or face - down Defense Position before adding the remaining cards to their respective hand . Yugi Set s a monster while Keith Special Summon s " Mechanicalchaser " ( 1850 / 800 ) and " Ground Attacker Bugroth " ( 1500 / 1000 ) in Attack Position . On Yugi ' s End Phase , he discards four cards in his hand as his hand surpasses the hand size limit . Turn 4 : Keith Keith draws . He then Normal Summon s " Machine King " ( 2200 / 2000 ) in Attack Position . Due to the effect of " Maching King " , it gains 100 ATK for each Machine - Type monster on the field . There are currently three ( " Machine King " : 2200 → 2500 / 2000 ) . " Machine King " attack s and destroy s Yugi ' s Set monster , " Silver Fang " ( 1200 / 800 ) . On Keith ' s End Phase , he discards two cards as his hand surpasses the hand size limit . Turn 5 : Yugi Yugi draws . He then Set s a monster . Turn 6 : Keith Keith draws " Megasonic Eye " and subsequently Normal Summons it ( 1500 / 1800 ) in Attack Position ( " Machine King " : 2500 → 2600 / 2000 ) . " Machine King " attack s and destroy s Yugi ' s Set monster , " Giant Soldier of Stone " ( 1300 / 2000 ) . Turn 7 : Yugi Yugi draws " Curse of Dragon " and subsequently Normal Summons it ( 2000 / 1500 ) in Attack Position . Yugi then Normal Summons " Gaia The Fierce Knight " ( 2300 / 2100 ) in Attack Position . He then activate s " Polymerization " to fuse " Curse of Dragon " with " Gaia The Fierce Knight " and Fusion Summon " Gaia the Dragon Champion " ( 2600 / 2100 ) in Attack Position . " Gaia the Dragon Champion " attack s and destroy s " Mechanicalchaser " ( Keith 2000 → 1250 ) ( " Machine King " : 2600 → 2500 / 2000 ) . Turn 8 : Keith Keith draws . He then switches " Megasonic Eye " and " Ground Attacker Bugroth " to Defense Position . Keith then activate s " Machine Conversion Factory " to increase the ATK and DEF of every Machine - Type monster he control s by 300 ( " Machine King " : 2500 → 2800 / 2000 → 2300 ; " Ground Attacker Bugroth " : 1500 → 1800 / 1000 → 1300 ; " Megasonic Eye " : 1500 → 1800 / 1800 → 2100 ) . " Machine King " attack s and destroy s " Gaia the Dragon Champion " ( Yugi 2000 → 1800 ) . Turn 9 : Yugi Yugi draws " Summoned Skull " . He then activate s " Makiu , the Magical Mist " to decrease the ATK and DEF every Machine - Type monster by 300 ( " Machine King " : 2800 → 2500 / 2300 → 2000 ; " Ground Attacker Bugroth " : 1800 → 1500 / 1300 → 1000 ; " Megasonic Eye " : 1800 → 1500 / 2100 → 1800 ) . He then Normal Summon s " Summoned Skull " ( 2500 / 1200 ) in Attack Position . " Summoned Skull " then gains 750 ATK due to the effect of " Makiu , the Magical Mist " ( " Summoned Skull " : 2500 → 3250 / 1200 ) . " Summoned Skull " attack s and destroy s " Machine King " ( Keith 1250 → 500 ) . On Yugi ' s End Phase , the effect of " Makiu " expires ( " Summoned Skull " : 3250 → 2500 / 1200 ) . Turn 10 : Keith Keith draws " Graceful Charity " and subsequently activates it to draw three cards and discard two cards ( he illegally placed three cards on top of his Deck right before drawing through the effect of " Graceful Charity " ) . Keith then activate s " Zera Ritual " to Tribute " Ground Attacker Bugroth " and " Megasonic Eye " in order to Ritual Summon " Zera the Mant " ( 2800 / 2300 ) in Attack Position . " Zera the Mant " attack s and destroy s " Summoned Skull " ( Yugi Muto 1800 → 1500 ) . " Duel concludes next episode . " Featured cards . The following cards appeared in this episode . Cards in italics debuted here .