Lava Mountain Zone has noticeably red skies in the area, with several dome-shaped structures found along its gray floors. Lava Mountain Zone also features several mountains and dormant volcanoes.
When Dr. Eggman first invaded the Lost Hex, he built a structure in Lava Mountain Zone as his main base of operations for the Eggman Empire. After he and his former enforcers, the Deadly Six, were defeated by Sonic the Hedgehog, the Zeti took over the base and remade it in their image, calling it "Zeti Castle".
The Last Minute
One day at Zeti Castle, Zor reported to Zavok that the Eggnet was in chaos due to Eggman's doings on the world below. The two were soon visited by a person named Dr. Starline. He introduced himself as an assistant to Eggman and requested that the Deadly Six help them with a current crisis that they were in. Starline let Zavok know that Eggman did not actually know he was on the Lost Hex but told him that working with the Eggman Empire once again would give the Deadly Six an opportunity to make ammends with the doctor, command incredible power and destroy Sonic. Hearing all of this made Zavok accept Starline's proposal. After the doctor left however, Zavok confided in Zor how Starline made a mistake and that they would capitalize on it.