Teleport Lapis

The Teleport Lapis is a Utility Psynergy item featured in Golden Sun: The Lost Age. It bestows the Teleport Psynergy, and it can be cast on certain large, circular stone patterns on the ground so that they can be used as "warp pads" that teleport the party to connected patterns. It is found in a chest in Mars Lighthouse, the final mainline dungeon in the game, and its use is required to complete the dungeon and, by extension, the game itself.

As soon as the Teleport Lapis is acquired, virtually all of the game's postgame opens up because the postgame dungeons Yampi Desert Cave, Islet Cave, and Anemos Inner Sanctum open up. Furthermore, having the Teleport Psynergy unlocks the significant quality-of-life feature of being able to bring both the entire party and the Lemurian Ship to any of the main towns and settlements of the game while in the overworld.