Egho Sanctum is a small island located northwest of Egho's main island. It connects to Seatide Ridge in the east.
The island has a platform in the middle surrounded by six pillars, many of which were severely damaged. The mysterious symbol marked on the platform is the same that is found in Egho's temples to the timespace deities.
It is first mentioned during a visit to Suncrest Isle, where the player gets told about the region history and the origin of the sanctum.
Oculeus only appears in Egho Sanctum if the player loses to it in the battle in the Unown Dimension. Shininess, IVs, nature, etc. will not carry over from the battle in the Unown Dimension.