When Ursa Zod became enraged at her solar pod being destroyed and slowing her gain of Kryptonian superpowers, it activated the Eye, which chose her. After Lor explained what he knew of the device from his time, Dru-Zod dubbed her the new Emerald Empress. Later, the Eye sensed the approach of Bio-Ship, but it took some time to communicate this to Ursa. Ursa used the Eye to shoot down the ship with a powerful blast of energy.
After Superboy refused to kill Superman, numerous heroes appeared to fight them. During the ensuing battle, the Empress faced off with Zatanna, who was outmatched by the Eye. Miss Martian then took on Ursa, creating an illusory self to be killed, allowing her to psychically attack her by surprise. Ursa fell unconscious and lost her link to the Eye. When she woke, the Eye put her in a bubble and flew away with her, against her protests.
Energy blasts: The Eye is capable of projecting powerful blasts of green energy.
Amplification: As Dru-Zod claimed the Earth as his, the Eye amplfied his speech.
Matter manipulation: Upon choosing her, the Eye changed Ursa's appearance, including the color of her eyes and hair length as well as creating new clothing. Later, Ursa used the Eye to change the crest on Superboy's solar suit from the House of El to the House of Zod.
Elemental conjuration: The Eye is able to create green flames and electrical discharges.
Space flight: The Eye can create a shield around the Empress to allow her to survive in the vacuum of space, and move at interstellar speeds.
The Emerald Eye of Ekron was the weapon of the Emerald Empress. Originally just a floating ball, it was later revealed to be a part of a skull-shaped spacecraft, an experimental weapon created by the Guardians of the Universe for the Green Lantern Ekron to aid him in his fight against Lady Styx.