Realizing they've been tricked, Tom and Thunder race into the God's Realm. They end up crashing into Jörmungandr hurting it so bad it loses one of its tusks and retreats. Still, Tom is frustrated Jörmungadr tricked him. Jun suggests that he has been focusing too hard on being Hiccup that he forgot he is a descendant of Astrid, too, suggesting he is more like her than Hiccup. With his self-doubts eliminated, Tom comes up with a new plan: To build an army against Jörmungadr. While his friends are off recruiting dragons, Tom and Thunder look for Jömrungandr. However, the Night Light's Alpha shows up attracting the Apex Predator before the other riders arrive. While the other riders manage to catch up and join the battle, the Night Light's Alpha ends up badly injured after shielding Tom and Thunder from Jörmungandr's fire breath. Before dying, he appoints Thunder as the next Alpha. As the battle continues, Buzzsaw returns to help the riders successfully cutting Jörmungandr. This, however, drives the dragon onto the surface attacking Rakke Town. Luckily, Thunder managed to recruit both the Fault Ripper and the Sky Torcher to fight against Jörmungandr. Together, they manage to deafeat the Apex Predator. However, Rakke Town is destroyed. That night, Jun and Tom make up and get back togther. However, the next morning, when they enter the cave, the dragons have decided to part ways with their riders having come to the conclusion humans and dragons cannot live together. Afterwards, while the former riders says their goodbyes to one another as Project I.C.A.R.I.S. has ended and only Director Wong and Olivia move on to the same project, Alex reveals she created a virtual place for them all to meet and stay in touch in which she named "The 10th Realm".
Tropes in this episode include:
- Back for the Finale: After 5 seasons of absence, the Fault Ripper makes its return and helps defeating Jörmungandr.
- Bequeathed Power: When the Night Light Alpha names Thunder as his successor before dying, he transfers his blue glowing aura and special abilities, such as sending out an EMP-pulse, to him.
- Be Yourself: Invoked by Jun after Tom has lost all hope in defeating Jörmungandr following the Apex Predator tricking him. Jun reminds Tom that he is not just a descendant of Hiccup but of Astrid, too, and goes on to tell him that he has much more in common with her than Hiccup. Thus, she suggests he should stop trying to be Hiccup and start channeling his inner Astrid thus embracing who he really is and try to solve the problem his way rather than Hiccups.
- The Big Damn Kiss: After defeating Jörmungadr, Tom and Jun sit at the Fissure. Tom thanks Jun for always being there for him and having his back. In responds, Jun tells him it seems she has to be his brains and kisses him.
- Bittersweet Ending: The riders and dragons defeat Jörmungandr and Tom and Jun get back together. However, Rakke Town is destroyed resulting in Project I.C.A.R.I.S. being terminated and the Dragon Club having to part ways. Further, their dragons decide to part ways with them, too, having come to the conclusion that humans are not ready to live together with dragons again as there will always be evil people trying to misuse them.
- Brains and Brawn: Invoked by Jun when she tells Tom it seems she has to be his brains.
- Does This Remind You of Anything?: The way the Dragon Club and their small dragon army defeat Jörmungandr is quite reminiscent of how Toothless and Hiccup defeated Drago's Bewilderbeast in How to Train Your Dragon 2: Before taking on Jörmungandr, Thunder rose to be an Alpha and started glowing blue. He then called the dragons to his side and commanded them to attack the Apex Predator. Though unlike the Bewilderbeast, Jörmungandr is then finished off via Thunder channeling his lightning through Tom's sword shocking the Apex Predator into unconciousness to be brought back to its prison.
- Electricity Knocks You Out: After having been weakend by the Spam Attack of the dragons, Jörmungandr is finished off by Thunder channeling his lightning through Tom's sword shooting it out as a beam electrocuting the Apex Predator into unconsciousness.
- Finale Credits: The end credits of the episode show sketches of the characters lifes after the end of the series. These include Tom and Jun on a date stargazing, D'Angelo helping an injured rhino, Eugene taking a selfie while playing chess with Alex, the Dragon Club meeting in Alex' virtual 10th Realm and the dragons living peacefully in the Hidden World.
- Grand Finale: This is the final episode of the show ending with the defeat of Jörmungandr, Tom and Jun getting back together, Project I.C.A.R.I.S. having come to an end resulting in the Dragon Club splitting up as their parents go on to different places and the dragons parting ways with their riders deciding humanity isn't ready yet for the return of the dragons to the world at large.
- Group Hug: At the end of the episode, the riders embrace in a group hug before leaving Rakke Town for good.
- Heroic BSoD: After realizing Jörmungandr tricked him and only just managing to get him to retreat, Tom lost all hope until Jun manages to pull him back up.
- Heroic Sacrifice: The Night Light Alpha shields Thunder and Tom from Jörmungandr's fire but gets mortally wounded in the process and eventually dies after appointing Thunder as his successor.
- Hold the Line: The Night Light Alpha attacks Jörmungandr before the other riders arrive with their recruited dragons forcing Thunder and Tom to both support him while also trying to keep Jörmungandr where he is and also stay alive until their reinforcement arrive.
- Offscreen Moment of Awesome: Thunder manages to convince the usually hostile Sky Torcher to help against Jörmungandr off-screen.
- Oh, Crap!: When Thunder faces Jörmungandr for the last time, now glowing blue symbolyzing his acension to the rank of Alpha, Jörmungandr looks surprised with a trace of fear in his eyes. Once Thunder commences the Spam Attack of his small force of dragons, the Apex Predator tries to run away rather than fight.
- Shared Family Quirks: A lampshaded example. When Jun tells Tom about who Astrid was, she tells him she was a fearless warrior who used action rather than ideas, not unlike Tom.
- Spam Attack: Jörmungandr is defeated by every dragon present focusing their Breath Weapon on him followed by Thunder channeling his lightning through Tom's sword and shooting it out as a beam.
- Stargazing Scene: The end credits show a scene of Jun and Tom on a date stargazing.
- Take Up My Sword: Before dying, the Night Light Alpha appoints Thunder as the new Alpha transferring its special abilities to Thunder.
- Taking the Bullet: The Night Light Alpha shields Thunder and Tom from Jörmungandr's Breath Weapon by flying in-between it and the two.
- Use Your Head: Thunder rams into Jörmungandr at full speed head first, knocking the Apex Predator down and one of its fangs out.
- What Happened to the Mouse?: Buzzsaw was last seen helping a couple of Gem Breaker after they were injured by Jörmungandr. What he did after the Apex Predator was defeated is unknown.
