In Fate/Grand Order Arcade, the Sega Luminasta Fate/Grand Order Arcade Re-run event featuring Alter Ego Larva/Tiamat is a special limited-time event. This event typically includes a re-run of previous content, where players can experience or re-experience specific story elements, challenges, and summonable Servants from past events.

Alter Ego Larva/Tiamat:

Alter Ego Larva is a version of Tiamat, one of the major antagonists from the Fate/Grand Order universe. She is a powerful and ancient figure from the Babylonian storyline, often depicted as a formidable force. In her "Larva" form, she may have a more subdued or less-developed persona, which contrasts with the fully realized form of Tiamat in the original story arcs.

In the context of Fate/Grand Order Arcade, this version of Tiamat likely brings her signature powers, formidable stats, and unique mechanics into the game for players to engage with. The event might feature special quests, story segments, and the opportunity to summon or battle against Alter Ego Larva/Tiamat.