The Eye of the Ancients is an enormous magical pendant-like object, and the final component of the Core of Light, first seen in Skylanders: SuperChargers. Alone, it has the power to enlarge itself and fire electrical spheres that stick to the ground.
When united with the Core, the Eye would turn it into a weapon, but the Ancients never completed the machine, and few knew of its true purpose throughout the centuries. Pomfrey, who researched the history of the Ancients, eventually discovered its most recent location in the Monstrous Isles, and with the threat of the Sky Eater, the Skylanders sought it out and retrieved it from the Titan known as Thunder Tow; however, the Eye was never placed in its rightful place, as the Core of Light was destroyed before the Skylanders could return to it.
Despite the Core of Light being rebuilt once again in the Sensei Light Realm, the Eye of the Ancients is nowhere to be seen.