Slifer the Sky Dragon ( manga character ) Slifer the Sky Dragon , known as Osiris the Sky Dragon ( オシリスの " Oshirisu no Tenkūryū " ) in the Japanese version , is a character in the " Yu - Gi - Oh ! " manga . It is one of most powerful monster spirits , the Egyptian God s . Its corresponding " Duel Monsters " card is " Slifer the Sky Dragon " , known as " Saint Dragon - The God of Osiris " , in the Japanese version . Biography . Slifer is a large , serpentine red - skinned , black - bellied dragon with spikes running down its body . Its wings are bat - like in form , with two thumb claws . Slifer ' s head has two mouths ; the bottom jaw of the smaller top set is part of the top jaw of the larger set . The last tooth at each cheek is larger than the others . Slifer ' s head is crested with four spikes protruding horizontally , and two larger ones from the back of the head curving vertically ; the sapphire common to the Egyptian Gods is nestled at the front of the crest . Its tail crest is shaped in a similar manner , but with a single flattened spike at the tip rather than two spikes . Slifer has short arms with three - toed feet . During " Yu - Gi - Oh ! Millennium World " , Slifer ' s spines are more constant , and it has hind limbs like its anime counterpart . Biography . Ancient Egypt . Slifer is one of the three Egyptian God s , along with The God of the Obelisk and The Sun Dragon Ra . These monsters were only capable of being summoned by the pharaoh . When Atem spotted Bakura , King of Thieves fleeing from the palace after he had attacked Aknadin , he chased after him on horseback and Summoned Slifer to fight Bakura ' s Diabound . Atem allowed Slifer to be struck in order to protect innocent civilians from Diabound ' s attacks and then got Slifer to force the battle into the sky . However Diabound was able to disappear into the darkness and attack Slifer from behind . Atem pretended to surrender his Millennium Pendant in order to distract Thief Bakura while he had Slifer sneak up on him . However Bakura got Diabound to make a similar sneak attack on the pharaoh . After the priests arrived , Atem sacrificed Slifer , so that Seto ' s Duos could attack Diabound , but Duos wound up hitting a decoy ka instead . By defeating Slifer , Diabound gained its power , including its " Thunder Force " attack . Battle City . 3000 years later , Maximillion J . Pegasus created cards depicting the three Egyptian Gods , for his game " Duel Monsters " . However the souls of the Gods came to dwell in the cards , making them powerful weapons . On realizing this , Pegasus regarded their creation as one of his greatest mistakes . He tried to destroy the God Cards , but could not bring himself to do it , so he had the Egyptian supreme council of antiquities bury the cards in different locations in the Valley of the Kings . The Rare Hunters managed to steal the " Slifer the Sky Dragon " and " The Sun Dragon Ra " cards . However the Egyptian supreme council of antiquities was able to prevent them finding " The God of the Obelisk " . Ishizu Ishtar , from the council , later gave it to Seto Kaiba , so that he would host the Battle City tournament to retrieve the other two . The leader of the Rare Hunters , Marik Ishtar , entered the Battle City tournament with the " Slifer " and " Ra " God cards . Using Doll as his puppet , he Dueled Dark Yugi in the preliminaries and used " Slifer the Sky Dragon " in the Duel . However Dark Yugi won the Duel and received the " Slifer " card through the tournament rules . Dark Yugi used " Slifer the Sky Dragon " in his semi final Duel against Dark Bakura . Summoning it and attacking Dark Bakura became Dark Yugi ' s only way of winning the Duel . Marik exploited this , by having Dark Bakura remove his control over Ryo Bakura ' s body . Ryo , who was injured and significantly weaker than Dark Bakura would not be able to withstand an attack from Slifer , making Dark Yugi reluctant to attack . However , Dark Bakura took back control of Ryo ' s body and urged him to attack , assuring him Ryo would be okay . During Dark Yugi and Kaiba ' s semi final Duel , when their cards " Slifer the Sky Dragon " and " The God of the Obelisk " destroyed each other , they were shown a vision of a past battle between Pharaoh Atem and Priest Seto . Dark Yugi also used " Slifer " in his final Duel against Dark Marik , though it was swiftly destroyed by " Egyptian God Phoenix " . Dark Yugi later revived " Slifer " to shield his " Obelisk " from one of the attacks from " Egyptian God Phoenix " . Project R . A . . When Yako Tenma Dueled Dark Yugi for the first time , Yugi Summoned " Slifer " by sacrificing his " Magna Warrior s " , though Yako remained calm and proceeded to Summon his own " God card " , " The Wicked Avatar " , which was initially in the shape of a black orb before taking on " Slifer ' s " form . Yugi attempted to use " Slifer ' s " second mouth to destroy " Avatar " , but the effect failed as " Avatar " was higher on the Divine Hierachy . " Avatar " then destroyed " Slifer " with a single attack , later revealed to be due to the " Avatar ' s " capability to take on the highest ATK on the field plus one . Although consistently mentioned alongside the other Egyptian God s , " Slifer " only made one more appearance , being used to offhandedly defeat Cedar Mill as Dark Yugi and Gekko Tenma raced to the top of the Kaiba Corporation building . World of Memories . When Dark Yugi entered the Memory World , he relived some of his life as Pharaoh Atem , and fought the battle against Thief Bakura , in which he Summoned Slifer , again . After relearning his true name from his friends , Atem blocked an attack from Zorc Necrophades and then Summoned the three Gods from the cards in Yugi Mutou ' s Deck . He then combined them into The Creator God of Light , Horakhty , who defeated Zorc . Yugi and Atem constructed separate Decks for the Ceremonial Battle , which Atem needed to lose in order to pass on to the afterlife . Despite needing to lose , Atem gave the Duel his all . He included " Slifer " in his Deck , and discarded it at the beginning of the Duel as the cost to Special Summon " The Tricky " . He revived it at the climax of the Duel , preparing to counterattack Yugi ' s " Silent Magician " , but Yugi prevented the activation of " Monster Reborn " with " Gold Sarcophagus " , sending " Slifer " back to the Graveyard and allowing him to win the Duel .