Sadre is the name of the underground tunnels below Erdas. You may take on quests in Sadre in the game. It has several bile animals to fight and almost always has spiders. The people who live underground in Sadre are called Sadreans, and their most prominent features are their white skin, white hair, and pink eyes. Sadre is overrun by The Many, who are revealed to be former Sadreans. The Wyrm parasites turn the Sadreans into the Many. Sadre's last major city, Phos Astos, fell to the Many in Immortal Guardians. It can be conjectured that Shane visited it with Yumaris, as he has a glowing purple mushroom in Venture.
- "Sadre" is Erdas spelled backwards.
- The Sadreans are scientifically diagnosed as albino, possibly because they have never seen the sun.