Grave Eclipse

The Grave Eclipse is a phenomenon in Golden Sun: Dark Dawn. When activated, a dark moon covers the sun with a dark aura, causing most of Angara to be enveloped by the aura, due to the activation of the Luna Tower. This, in turn, causes thousands of vicious monsters to appear in the dark areas, ruthlessly slaughtering anyone who approaches them. It can only be activated by using the Magma Orb, and the pedestal where the orb must be placed to activate the eclipse is located deep within the Belinsk Ruins, in the Alchemy Dynamo. The ruins were sealed up years before the game begins, to prevent anyone from entering them and activating the Alchemy machine. Matthew and his friends are tricked into retrieving the Magma Orb from within the Mountain Roc by Blados and Chalis for the purpose of activating the eclipse. At the Alchemy Dynamo, Blados and Chalis arrive with Arcanus to distract Matthew and co. while Arcanus manipulates Ryu Kou into placing the orb onto the pedestal, thereby triggering what becomes known as the Grave Eclipse. Luna Tower can only be deactivated by use of the Apollo Lens, a machine located at the Apollo Sanctum. The lens can only be activated by use of three orbs: the Blue Orb, Red Orb, and Yellow Orb. Matthew and co. eventually make their way to the sanctum, place all three orbs in their pedestals, and reactivate the lens. After the final battle, they use the lens to deactivate Luna Tower, thus putting an end to the eclipse.

Arcanus seems to want the Apollo Lens reactivated and used to end the eclipse, despite having a hand in starting it, though the reason why is unclear. Also after the final battle, when Matthew attempts to climb up to the lens, he warns him not to keep trying, and after a couple lines, nothing is heard from him for the rest of the game.