In Fire Emblem: Echoes: Shadows of Valentia, what is the name of the secret dungeon?

The secret dungeon in Fire Emblem Echoes: Shadows of Valentia is Thabes Labyrinth. It is an optional, high-level dungeon that becomes available near the end of the game and provides the remake’s major post-game challenge.

Unlike the campaign’s standard grid-based battles, Thabes Labyrinth uses a third-person exploration format. Alm and Celica’s army moves through interconnected rooms, encounters enemies, collects items, and searches for a route through the dangerous complex. The dungeon combines exploration, combat, and resource management, making it substantially different from the main story chapters.

Thabes Labyrinth is also important to the game’s wider mythology. Its depths contain powerful enemies and story revelations connected to the ancient dragon Grima, linking Shadows of Valentia to the later events of Fire Emblem Awakening. Fear Mountain, Dragon’s Maw, and Mila’s Temple are other locations or dungeon-like areas, but none is the secret endgame labyrinth named in the question.