Possessed Nayru

Although never named directly so in Oracle of Ages, Possessed Nayru is a fanon name given to Nayru while she is possessed by Veran. She was initially possessed in the opening scenes of the game, where the handful of witnesses included Impa, Ralph and Link. Everyone else, aside from the nearly-omniscient Maku Tree, is unaware of the possession, and still believe she is the pure Oracle of Ages. With Nayru serving as her cloak, Veran begins to malevolently advise Queen Ambi's decisions in the past, which affect both the past age's citizens, and the present age in which Link initially resides.

One notable influence Veran gave was to seal off Ambi's Palace from casual visitors, barring both Link and Ralph from attacking Veran directly. Another was to discreetly confiscate all Mystery Seeds -- the only known way to harm a possessing Veran without also hurting the possessed. Early in the game, Link unknowingly offered his seeds to the Queen and her adviser in order to temporarily enter the Palace and meet Veran face-to-face. He was still able to gain more Mystery Seeds later in the game, however.

After Level Six, Queen Ambi leaves her Palace, dropping the guard enough for Link to penetrate the castle's defenses and reach Possessed Nayru. Once Link is victorious in the ensuing battle, Nayru will be freed from Veran's grasp, and teach Link the Tune of Ages. Veran herself will instead possess Queen Ambi, a possession that will remain until the significantly tougher final boss fight in Black Tower.

Strategy
Possessed Nayru's only attack consists of shooting fireballs in a radial pattern. The projectiles spread out the further they travel, and Link's shield can't block them, so it's best to walk in the gaps that form at a distance.

The only way to attack Veran herself is by shooting her with Mystery Seeds from Link's Seed Shooter. If hit, Veran will temporarily loose her possession, but she'll seep back into Nayru if you're not fast. By switching places with her via the Long Hook, she'll have a tougher time getting back to the body, and Link will have the opportunity to slash her at least once. Even so, Posssessed Nayru will often hide behind pillars scattered across the room while she prepares an attack, making it harder to hit her with the Seed Shooter and Long Hook fast enough to get an attack in. If the attack process is repeated three times, Veran will be temporarily defeated, and Naryu will be freed.