In episode 87, Odion uses this card during his Duel against Joey Wheeler. He summons this card through the effect of "Seal of Serket". In the next episode, this card attacks and destroys "Jinzo". This card then gained ATK equal to half of the ATK of "Jinzo". On Odion's next turn, this card attacks and destroys "Insect Queen". This card then gained ATK equal to half of the ATK of "Insect Queen". On Odion's next turn, this card attacks and destroys "The Legendary Fisherman". This card then gained ATK equal to half of the ATK of "The Legendary Fisherman". On the last turn of the duel, Odion was going to use this card to attack directly, but Marik told him mentally that he had to play "The Winged Dragon of Ra" to protect his identity. In the following episode, Odion uses the effect of "Temple of the Kings" to Tribute this card and Tribute Summon "The Winged Dragon of Ra" (This card counted as three tributes for the summon because it destroyed three of Joey's monsters).
In the third above-mentioned episode, this card appears in a series of flashbacks Odion has when he explains that this card counts as three Tributes due to it absorbing three of Joey's monsters which was why he could Tribute this card to summon "The Winged Dragon of Ra".
In episode 124, this card is shown in a flashback that Joey has when he remembers all the Duelists he faced on his way to the Battle City Finals.
"Mystical Beast of Serket" could only be Special Summoned by sending a Face-up "Cup of Sealed Soul" and "Seal of Serket" to the Graveyard. In the anime it gained ATK equal to half of the ATK of the monster it Destroyed in battle. In the real game its ATK only increases by 500. It could also serve as Tributes by an amount equal to the number of monsters it destroyed (e.g., if it destroyed two monsters, it can serve as two Tributes).
In the original Japanese version of Episode 88, "Serket" had ???DEF when it was first summoned.
In the anime, when this card attacks a monster, it grabs the opposing monster and eats it (in the dub, it absorbs the opposing monster). When this card gains ATK equal to half the ATK of the monster it destroyed in the anime, it gains some of the qualities of the monster it destroyed.
Mystical Beast of Serket appears as a playable monster in The Falsebound Kingdom. It is unlocked during Joey's side of the story by defeating Odion as Joey. Serket has two moves; "Relinquished Eater", its attack, and "Tribute Soul", which uses two action points to power up.