Aiwass's mind flashed with information about this dungeon.
This dungeon is called [Blood Altar Ancient Ruins]. It's not a main storyline dungeon but rather the type designed for quick runs to reliably produce the final piece of a Priest's level 50 endgame gear—it belongs to the Fallen Celestial Marshal expansion.
After the Fallen Celestial Marshal descended, the leyline mana flow in many areas of Star Antimony went out of control. This caused a series of earthquakes, resulting in numerous underground ruins cracking open once more, allowing Prophets to pinpoint precise locations. As a result, many dungeons with suffixes like "Ancient Ruins" or "Primordial Ruins" were created.