Veran

Veran is the antagonist of Oracle of Ages. She is the Sorceress of Shadows and possesses the ability to possess people (including Impa, Nayru, and Queen Ambi). She first meets Link while controlling Impa and tricks him into moving a boulder that can only be moved by "One who bears the Triforce". She then tricked him into getting close to Nayru, and then let go of Impa to seek her new host. Once she takes control of Nayru, she travels back in time to alter history.

As Nayru, Veran tricks Queen Ambi into trusting her and beginning construction on the Black Tower. Just before the Black Tower was completed, Link eventually came face-to-face with her, in Ambi's Palace, but Veran tells him that if he were to attack her, only Nayru would bear the damage. However, Link had found out about Veran's weakness, and was able to utilize it correctly, driving her from Nayru, almost immediately into Queen Ambi herself. Taking full advantage of her situation, Veran was able to drive Link, Nayru and Ralph, who had burst into the palace at the same time as Link, away, Nayru rescuing them all to the disapointment of Veran. As Link continued to finish his quest, the Black Tower reached completion as the seventh Essence became his.

At this point, Veran had gained the power to control time to an extent, even without Nayru, freezing many in time as she cultivated her new power. However, after Link obtained the eighth essence, another face confronted Veran before he could: Ralph.

Although Ralph knew that, by killing Queen Ambi, and thus Veran, he would vanish, he cared only for the people of Labrynna, and so attempted to kill her, ultimately failing. However, due to Veran's 'generosity', Ralph lived on, and Veran moved on to face Link. After a long battle, during which the unimaginable true forms of Veran were revealed, Ambi was freed, and Veran was defeated. However, like Dark Dragon, Veran simply laughed, calling Link a fool as she died, her task complete. The revival of Ganon was simply closer to fruition.

Strategy
Veran has several different strategies, depending on which form she is in.

Possessed Ambi
The strategy for Ambi was little different than it was for Nayru. As Ambi, the only new ability Veran obtained was the ability to summon small and annoying spiders. Besides this, the strategy is still to use Mystery Seeds when she stops moving, then to use the Switch Hook to pull Veran out of Ambi.

True Form
As soon as Ambi flees the room, free of Veran, Veran will move to possess Link, missing by a breath. Commending him on coming so far, Veran will now reveal her true form.

Veran's true form is fairly simple to defeat. Taking on the form of a demonic fairy, Veran is now accompanied by four Dark Links, which act as little more than Arm-Mimics. To defeat this form, Link simply had to attack her with his sword whenever she came into range, taking care to dodge her attacks when she attacked. By repeating this method, Veran appeared to be defeated. As Link, Ralph and Nayru exited the Black Tower, a sudden rumbling had Link push Ralph and Nayru away, as a Wallmaster carried Link back to the top.

Metamorphosis
As the Wallmaster released Link, a truly horrific side of Veran was revealed, as she appeared to Link in the forms she had wished to keep a secret from everybody. Now, with no other choice before her, Veran revealed her Metamorphosis state.

Beetle
As little more than an oversized, grotesque beetle in this form, Link quickly realised that all Veran could do now was jump and land, albeit hard enough to create a pool of acid underneath her. By attacking her face when she emerged with the sword, she would then transform into one of two forms.

Bee
One of three of Veran's metamorphosis forms, Veran's weakness remains her head, which must be attacked with the sword. However, the bee form is faster than the beetle form, able to move alarmingly fast at times. Its main attack is a barrage of stingers. If this is the first form Veran takes, then she will likely revert to her turtle form then take her next form, if she still has enough life left. If not, this should be Veran's downfall. However, Veran is prone to changing form randomly, rather than being forced into it.

Spider
Arguably Veran's hardest form, this state has no obvious weak point at first. Its attacks include high-speed charges and using web to pull itself onto the Tower roof, then slamming down in an attempt to crush Link.

Out of all the weapons in Link's inventory, the only one which can reveal Veran's weak spot is one of his bombs. By using a bomb on this state, Veran would show her face for a few valuable seconds, allowing Link to attack her with his sword. After Veran had taken enough damage, given her life, she will either revert to her turtle form or she will fall.

Trivia

 * Though Veran bears the Gerudo symbol, her true form is that of a demonic fairy. However, her human form somewhat resembles that of a Twili.
 * Curiously, Link never fights Veran in her normal form, besides the few attacks he inflicts on her after forcibly removing her from Ambi or Nayru's body.
 * The four Dark Links Veran's True Form summons always give off one heart each on their defeat.
 * There is debate as to whether Veran's true form is what she refers to as her true form, or Metamorphosis. In-game, Veran does mention she wishes to keep metamorphosis a secret...
 * More often than not, the spiders that Ambi summons will give Link bombs upon their death, subtly hinting of Spider Veran's weakness.