Friendship is the true magic!
Continuing from the previous episode, Bloom, Flora, Nereus, and Serena pursue Tritannus. The others were left behind defending the Pillar of Light. Bloom tells Flora to go and assist them while they continue to chase Tritannus and Icy. They had to get to the Emperor's Throne before it is too late. Tritannus also took his cousin, Aisha to use her Sirenx power to activate the throne and now the others must free Aisha before Tritannus takes over the Magic Dimension.
At the Emperor's Throne, Princess Aisha is held prisoner in the same cell as Daphne. Tritannus and Icy began having dreams of grandeur as they were close to activating the throne. Tritannus sits upon it and uses his trident to activate the throne, causing a wave of darkness that blew Icy back.At the Pillar of Light, Stella, Flora, Musa, Tressa, and the Selkies face off against the remaining mutant slaves. The darkness wave suddenly passes over them, causing the mutants to act strange. Another gate appeared, and the mutants leave through it. Stella and the others quickly follow. At the Emperor's Throne, Icy witnessed Tritannus suddenly bulking up due to the power absorption. She gets excited and says she is ready to rule over the Infinite Ocean, However, the power had made Tritannus get out of control and attacks Icy, much to her horror. She tries to talk with him, but he was beyond reason now and mercilessly began to attack her, causing Icy to fear for her life. Just as she was about to get killed, she was saved by none other than Darcy and Stormy, after a long absence Icy was surprised by this, since they did not exactly part on good terms. Darcy bluntly states that they still are mad at Icy, but despite that, they are still sisters, and still the Trix. They attack Tritannus, but to their horror, he just absorbs their shots, then fires a shot of his own at them, effectively ejecting the Trix from the Infinite Ocean. Completely power mad, he invades Andros.
Stella, Flora, Musa, Tecna, Tressa, and the Selkies arrive in the waters of Andros, confused as to why they wound up there. They find the mutant slaves swimming towards the shore, where Tressa realized they were going after Aisha's parents, Teredor and Niobe. They quickly swim for the Andros Palace.
The sea level around the Andros Palace soon began to rise, threatening to flood it. The mermaid guards were forced to defend against the mutants. Inside the palace, Teredor and Niobe were trapped in the throne room, but quickly escape before it gets flooded.Bloom, Nereus, and Serena arrive at the Emperor's Throne, where they witnessed the now powered-up Tritannus. Bloom directs Serena to find Aisha and Daphne while she and Nereus deal with Tritannus. Bloom fights against some mutants while Nereus once again faces his corrupted twin brother. At Andros Palace, the mermaid guards were cornered by the mutants, but then get assistance from Roy. More mutants show up and a fight breaks out. Tressa soon arrives with Stella, Flora, Musa, and Tecna. The fighting escalates, then Roy tells the Winx they will hold them off while they go find Teredor and Niobe.
Soon, the entire palace was nearly flooded completely, Teredor and Niobe had retreated into the tallest tower of the palace, but it was only a matter of time before it would go under as well. The floor soon began to slowly flood, causing Niobe to panic, then panics even further when some mutants break through the wall and attack. Teredor grabs a nearby spear to fend off the mutants until the four Winx arrive. After repelling the mutants, Stella encases the king and queen in a globe of light and fly them out of the tower just as the entire palace is completely flooded. The four Winx were shocked to see even more mutants show up to fight Roy and the mermaid guards. Stella leads the girls to fight off the mutant waves.Nereus battles against Tritannus. Even with Bloom's help, Tritannus is unharmed and laughs off their attacks. She changes tactics and tells Nereus they have to separate Tritannus from his trident and destroy it. Nereus rushes Tritannus, and after a bit of effort, he managed to disarm his brother of his weapon. Bloom then quickly uses her Sirenix spell on the trident, then destroying it. The pollution vanished, and Aisha and Daphne were freed of their bonds. The cell opens as Serena swims to them. The mutant slaves Bloom fought off earlier reverted back into King Neptune and Queen Ligea. Nereus happily reunites with them. As for Tritannus, he gets surrounded by everyone as he began to rant about how he should have easily killed them all, then painfully reverts back to his original merman form. On Andros, the water level recedes, and the mutant slaves revert back to their former selves again. Everybody cheered at the victory and Tritannus' defeat. Teredor and Niobe come down to greet their subjects, then they were met with the appearance of the now restored Neptune and Ligea, whom Tressa tearfully reunites with. Teredor was glad to see his brother all right, then Bloom, Aisha, Nereus, and Daphne show up, with Tritannus in custody. Everyone glares at the once again disgraced prince as Teredor condemns him. Nereus demands if his brother had anything to say in his defense for his crimes, which Tritannus snidely states that he is only sorry he did not kill them all when he had the chance. Seeing he had absolutely no remorse for what he had done, Teredor decreed to banish Tritannus from the magic dimension, Neptune then passed judgement on his disowned son: He will be forever banished from the magical universe and will live out the remainder of his life beyond the dark Gate of Oblivion, never to return. Tritannus is escorted by some guards, and the Winx Club to the Gate of Oblivion. He is forced through the gate, with Aisha commenting that it was what he deserved. Bloom's Guardian of Sirenix appeared and offered her a Sirenix wish. She uses her wish to break the Sirenix curse and end its dark legacy forever. As a result, Daphne appears before her, and is restored to her physical body of solid flesh and blood, finally restoring her to her true self at long last. Bloom tearfully reunites with her long-lost elder sister, after five seasons and two movies, they can actually touch each other.
At a seaside stage near Andros Palace, the royals of the Magic Dimension and the students and faculties of the three schools of Magix attend a victory celebration where Neptune declares that the planets of the Magic Dimension will from now on stand united as one family. Oritel, Marion, and Daphne arrive with Mike, Vanessa, and Kiko. Mike wonders where Bloom and the Winx are, and Sky merely replied they are on stage. Mike was confused, as he could not see any stage. Suddenly, a stage emerges from the pool in the center, with the Winx complete with band instruments.The Winx perform "The Magic of Tonight", while the Specialists, the other Alfea fairies (including Roxy and Krystal), and their families are seen cheering. Near the end of the song, Bloom flies over to her big sister, and they are seen happily dancing together.
- Tritannus successfully activates the Emperor's Throne and becomes a monster; both in body and spirit.
- Bloom uses her special Sirenix spell, Fire of Sirenix, to destroy Tritannus' trident.
- Tritannus' trident is destroyed; thus he is ultimately defeated.
- All of the mutants return to their original forms.
- Nereus and Tressa are happily reunited with their parents.
- Tritannus is banished to Oblivion.
- Bloom wishes that she can break the Sirenix curse and end its legacy forever, bringing Daphne back to her physical form again.
- Daphne is restored to her physical body at long last.
- The royal families, the staffs of Alfea, the people from the underwater kingdom and the Winx celebrate after defeating Tritannus.
- Daphne (physical, living body of solid flesh and blood)
- King Neptune (3D form)
- Queen Ligea (3D form)
- Winx Club
- Bloom's Guardian of Sirenix
- Deafening Chord - Used by Musa twice against the Mutant's.
- Petal Hurricane - Used by Flora against the Mutants.
- Dark Sirenix Convergence - Used by the Trix against Tritannus.
- Dancing Flames - Used by Bloom to defend herself.
- Spring Banner - Used by Flora to defend Roy and the guardian mermaids.
- Logic Net - Used by Tecna to stop the guardian mermaid from falling.
- Light Diamond - Used by Stella against a mutant.
- Gaia's Defense - Used by Flora against the mutants.
- Wall of Sound - Used by Musa against the mutants.
- Dragon Kick - Used by Bloom against Tritannus.
- Dragon Punch - Used by Bloom against Tritannus.
- Lava Jab - Used by Bloom against Tritannus.
- Fire of Sirenix - Used by Bloom to destroy Tritannus' trident.
- Darcy and Stormy return and reconcile with Icy.
- The mermaid guards of Andros make their first appearance since Season 3.
- This is the first time Queen Ligea and King Neptune are seen in 3D.
- This episode marks the last appearance of the Selkies for the series and they will return in the third Winx Club movie.
- This is the last time the Winx are in the Infinite Ocean in this season but they will return in the third Winx Club movie.
- In the Nickelodeon's clip for "The End of Tritannus", the title is "Ocean Takeover".
- The alternative title for this episode was titled as "True Magic".
- It is unknown that where did Riven get his guitar during the concert.
- While underwater in 2D, Bloom has her hair recolored in light green with purple streaks instead of carrot orange.
- While underwater in 2D, Tecna has her hair recolored in dark blue instead of light purple.
- In one scene, Musa's armband was missing.
- In the Italian version, when Tritannus hits Icy with his hand, he says "No!". However, in the English version, he says nothing at all.
- In one scene, the Singing Whales are seen at the Infinite Ocean, while they should have been on Melody.
- When the kings are deciding what punishment they should give to Tritannus, Bloom's arm ribbon is on her left arm.
- Also, Aisha's arm ribbon is on her left hand.
- When Bloom's sirenix guardian appears, Aisha is missing.
- In the middle of the concert, Helia creates a paper bird and sends it to the Winx. However, in the next scene, he is shown standing near the pool and the paper bird is flying from another direction.
- During the concert, Bloom's mouth does not match her singing.
- Kiko wears a coat when he's dancing on the stage. However, at the end, his coat is missing.
“Best little sister in the known universe!”