Hydra Constellation
From WikiRaider
The Hydra Constellation is an Artifact in Shadow of the Tomb Raider. It is part of the Path of the Stars collection. It can be found in Cozumel.
This is the star Alphard, the solitary one. The brightest star in the Western sky and the "Heart" of the Hydra constellation. Two thousand years ago it set in the west. That's where I hope to find the hidden city.
Artefact description in the game inventory