He only appears in-game after the player claims his Character Unlock Mission reward for activating Trap Cards 300 times.
Odion is the servant of the Ishtar family and has sworn his allegiance to Marik. An honest Duelist who Duels fair and square, his Deck is comprised of Trap Monsters, such as "Embodiment of Apophis", to ensnare his unsuspecting opponents.
Immediately after the player claims the reward for Odion's appropriate Character Unlock Mission, they will encounter Odion for the first time. At the time, he is engaged in a Duel with Jay, the latter struggling against him. After Odion defeats Jay with his "Judgment of Anubis" card, Odion reveals that he himself never thought he'd be able to Duel again after all the darkness he experienced. He then wonders if his own presence in Duel World means that "Master Marik" is in Duel World as well.
Until the player defeats Odion for the first time, whenever they challenge Odion to a Duel, he will observe that the player is a noble Duelist, one that is worthy of battling. He tells the player that he'll show the player what he's capable of, if they wish to Duel him, but also warns the player that they may come to regret their decision. He then asks the player if they still have the courage to Duel him, before accepting the situation and declaring that they should begin.
Upon Odion's first defeat, he remarks that the player's tactics were most impressive. He goes on to claim that since the player showed no fear against his strategies, that proves they are an honorable Duelist. Odion then declares that it was his privilege to Duel the player, before prompting the player to continue their journey and seek their glory.
After the player redeems their final unclaimed reward for Odion's Character Unlock Missions, they will encounter Odion again, who tells the player that even when people are lost in the darkness, those people must not lose their will to fight for the light, something which he proclaims he's done his whole life. He recommends that this is something the player should do as well. Odion goes on to declare that fighting for the light is fighting for one's own existence, and that he himself will keep fighting with his "Embodiment of Apophis" card. He concludes his dialogue by stating his quest for the light shall never end.
Can be used each time you activate a Trap card. Decreases your opponent's Life Points by 200.
Draw Sense: Spell/Trap
Can be used each time your Life Points decrease by 1800. In the Draw Phase, instead of doing a normal draw, draw a random Spell/Trap card.
Endless Trap Inferno
Can be used each time your 3 trap cards are sent to the graveyard. A random trap card in your graveyard is shuffled into your deck.
Can be used each time your Life Points decrease by 1200. Statue of the Wicked is set in your Spell & Trap Zone.
Whenever Odion Special Summons "Embodiment of Apophis", a cut-in frame of Odion will appear, where he'll announce "There's no escaping from its rage!" followed by "I activate my trap, Embodiment of Apophis!" If that player hasn't already Summoned "Embodiment of Apophis" during that Duel, a cutscene of "Embodiment of Apophis" being Summoned will play afterwards.
Whenever he declares an attack with that monster, he'll announce "I attack with Embodiment of Apophis!"