In Jim time past adventure, he's been traveling with Callista ever since they've escaped from Camelot. One day they ran into a refugee where he meets Blinky and his twin brother. Unfortunately they weren't welcome due to Callista activities of bringing trouble. Soon Aarg, sent by Gunmar, attacks the refugee home to force the trolls to join or die. Jim and Callista fought Aarg until he gave up before Vendel announce Blinky to watch over the prisoner. Vendel also decided to see if he can help Jim from the shard since he has knowledge of healing people.

Vendel: Your wound is festering with dark magic.

Jim: I- I don't know if that's necessary.

Vendel: Oh, it's no trouble at all. You're lucky to be alive. I've always wanted to use these.

Callista: Here, bite down on this.

Callista shoved a bone on Jim to bite for the process. But before they could begin, they were interrupted when a portal opened and Claire arrives with her team along with Merlin and king Arthur.

Claire: Hey, that's my boyfriend you're operating on!

Vendel: Oh! Humans! Sound the alarm!

Arthur: Hold! Please, Vendel of Dwoza. I humble myself before you. Camelot needs your help.

Arthur: Gunmar the Black's swarm of Gumm-Gumms are ready to strike. The monsters seek vengeance on both our kind.

Vendel: And after all you've done, you expect us Trolls to fight this war for you?

Arthur: No, not for me; with me, as equals.

Vendel: Glorkus me!

Arthur: I vow, if we win this war, we shall live in peace.

Callista throws a rock at one of the knights and chuckles before Bagdwella stop her.

Bagdwella: Move your rocky butt, Calamity! (Notice humans and gasp.) Hu-hu-humans! It's an infestation!

Dictatious: No, I believe it's a negotiation. (Gasps.) By Gorgus, the king seeks an alliance! Are they mad?

Vendel: Gumm-Gumms are terrifying warriors while we are but humble gravel miners. How do you expect us to ever defeat Gunmar?

Arthur: We will give you a secret weapon.

Dictatious: A weapon?

Meanwhile the future pals are discussing outside of the conversation.

Jim: You really think they can work this out?

Douxie: They have to, or everyone in Camelot and Dwoza are doomed.

Claire: Then so is saving history.

YN: No history, no going back home.

Claire: Great.

Merlin: I assure you, all will be fine once I've completed my amulet.

The old wizard then notice Jim.

Merlin: So, this is the once and future Trollhunter I've heard of. May I have a word, alone?

Jim: Um, sure. Be right back.

Jim and Merlin leaves to have a talk alone I'm private.

Callista: I can't believe it. Arthur wants us Trolls fighting alongside his big, shiny knights like heroes?

Bagdwella: Us? No one's asking you to fight, No-Name.

Dictatious: I knew you were cursed, Callista. You've brought outsiders and their war into our home!

With Merlin and Jim, they are discussing something which leads to bad news for Jim.

Jim: So, that's it, then. (Sighs.) Thanks for trying, Merl.

Claire: Hey, is everything okay?

The future humans enters to hear what's going on.

Claire: What are you talking about?

Jim: Oh, um nothing. Just Merlin prepping me for the trip home.

Douxie: Wait, wait, wait, you finally finished the Heart of Avalon? It's working?

Merlin: Indeed. But first, we must survive the battle to come.

Arthur: Wizard we've reached an agreement. Now you must convince the crowd.

It didn't take too long for all the trolls to gather around to hear the announcement.

Vendel: Trolls of Dwoza, hear us now!

Arthur: As we speak, death comes for us all. But we bring an offer of hope.

Douxie: Here comes the light show!

Douxie uses magic to show them the amulet construct before Merlin speaks.

Merlin: I've designed a grand weapon, an amulet which will choose the greatest warrior among you to banish the Gumm-Gumm menace from our realm and become the Trollhunter!

Draal: Trollhunter?

Arthur: The amulet's power will activate Killahead Bridge, once a border between our worlds, turning it into a magic prison for Gunmar and his brood, trapping them in the Darklands and ending this war!

Callista: Wow. We would finally have peace? No more bloodshed, no more dungeons The Trollhunter could save our kind.

Draal: Stop gawking, outsider. I, Draal, Dwoza's strongest, shall be chosen for glory!

Vendel: The battle will not be easy. While the wizard builds this am-yoo-let, the king's men will train our bravest.

Lancelot: Indeed. I shall guide the-

Steve: Yeah! Knights Steve and Lance here to whip you big hosses into warriors! Krav Maga! Turtle stance! Whoo! Ah! Hee-yaw!

Arthur: Then we ride for Killahead to draw Gunmar out.

Everyone cheers and get started with the preparation.

Archie: Well, it seems we may have a shot at surviving this after all.

Merlin: One shot is the best I can offer. When Killahead activates, it shall unleash a surge of magic across the realm.

Douxie: Just enough to power the Heart of Avalon for a trip through time.

Merlin: But only one, which means everything must go according to my plan. Hisirdoux, with me. I need your assistance.

Claire: (To Jim.) At least we're reunited. We'll get through this together.

The couples hug before Claire continue speaking.

Claire: Come on, I wanna take you somewhere.

Douxie: Uh, you two take a beat. Merlin and I have still got to actually finish the amulet all our hopes are riding on.

YN: You do that. Toph and I will plan out a strategy with the rest of the earthbenders.

Everyone part their ways to do their part.

Time skip

Steve and Lancelot train the trolls for the amulet preparation while Jim and Claire are having a small date where she teleported them to where Jim's house would be which is at the other side of the world. YN and Toph are planning a strategy for the battlefield while we see Merlin and Douxie are working on the pieces of the amulet before the head to the round table that have gemstones with each different colors.

Merlim: The gems have the exact resonance and light transmissions we require. Which one speaks to you?

Douxie run his hand around the table until the feels one that has a strong bond with him. Revealing a blue gemstone.

Douxie: This one.

They remove the gemstone and uses it with Merlin combination gem energy as it release an energy beam.

Merlin: Quick! Harvest the wave!

Douxie does so, doing his best to maintain it with the blue gemstone.

Merlin: Do not lose it!

Once the green energy beam comes contact with blue gemstone, it release a blue energy beam.

Merlin: Hold steady!

They use the energy beam to carve the amulet gemstone while giving it energy. Afterwards, Douxie holds Morgana's severed hand and toss it in the molten metal to liquefy.

Merlin: Ironic. Morgana fought against the amulet. Now she helps power it.

Douxie: (Chuckles.) At least she could
lend a hand, eh?

The old wizard couldn't help but chuckles at his apprentices joke before he leaves to receive something for him.

Merlin: There is but one final step. To lock the amulet together, two master wizards are required.

Merlin hold out a new staff with the blue gemstone for Douxie.

Archie: By Ambrosius' Gleaming...

Douxie: Is that...Is that for me?

Merlin: Thought you'd make something of it. You've done great things with less, like that bracelet of yours.

Douxie: No, I, uh I can't accept this. I'm not worthy.

Merlin: That humility is exactly why it belongs to you.

With enough courage, Douxie uses his bracelet to bond it with his new staff so that he can summon it whenever he needs to.

Merlin: Let us finish this, Master Wizard.

All that's left is to put the amulet together with their magic combine and successfully created it.

Merlin: Now come along. It is time for the amulet to choose our champion.

Afterwards, they head back to the trolls lair to give the trolls the weapon.

Merlin: Today, the amulet will choose one of you to defend your people, to hunt these Trolls who have betrayed your kind. You will no longer fear the daylight. You will wield it as the Trollhunter.

Callista: Let's see which of you brown-snouters gets picked.

Draal: It would be my honor.

Troll: I am ready.

Douxie: For the Glory of Merlin awake.

The amulet begins to glow and float around where it seeks a worthy troll until it stops to Callista.

Amulet: Rise, Trollhunter and become.

Callista: Uh, I think your amulet has the wrong Troll.

Merlin: No, the amulet does not make mistakes. For whatever reason, it has chosen you.

The troll holds the amulet.

Merlin: Speak the incantation. Find your purpose, the savior of our worlds.

Callista: Me? (Scoffs.) I've never been chosen for anything.

She reads the writing on the edge of the amulet.

Callista: "For the Glory of-"

Draal: Bushigal! It chose Callista the Calamity? She's basically a fleshbag.

Troll: This is the humans' big plan? The only place that outsider will lead us is death!

Merlin: Ignore them. Accept this honor.

Callista: No, they're right, I'm not a hero. I'm not even good at being a Troll.

Merlin: Go on, say the words!

Jim: Cal, wait!

Callista: I...I can't do this!

She runs away before the amulet follows her. The wizards follow but Vendel stops them.

Vendel: Is this some sick human joke? I believe you fleshbags have done enough damage.

2nd troll: We're doomed!

Draal: Gumm-Gumms are coming for us and we've wasted time with your silly games!

3rd troll: We must hide!

Merlin: We all must fight as allies.

Vendel: You think just because your king gives us a shiny toy, you can buy our loyalty? Leave, and take your trinkets with you!

Arthur, giving up, decided to leave.

Arthur: These creatures will never trust me. Why should they? This was a mistake.

Archie: The amulet chose Callista?

Claire: Whoa, whoa, whoa, wasn't Deya the first Trollhunter?

YN: It makes no sense.

Douxie: Either way, without one, Killahead will be a bloodbath.

Jim: I think I know where Callista went. Claire?

Claire nods and create a portal for them to leave while Douxie, YN, and Archie are behind

Archie: What about the king? Doesn't history need him at Killahead as well?

Douxie: Don't worry, I'm on it.

YN: I'll see where he is.

Douxie: Then let's go.

YN uses his seismic senses to detect Arthur before they head out. Soon they arrive to the cliff side where Arthur accidentally killed his sister. Douxie holds the crown that was dropped by Arthur before he speaks to the king.

Douxie: Reflecting, my king?

Arthur: I was convinced magic had taken everything from me but it was my own doing. I tried to protect my people at the expense of so many others. Morgana was right. She wasn't evil...I was.

Douxie: It's true you've done questionable things, but the fight's not over yet. There's still time to make things right for those you've wronged. Help me save them.

Arthur: (Curious.) Who are you, boy?

Douxie: I am Hisir-....I'm nobody. History won't remember me. Stories won't be told about me, but I won't let that stop me from fighting for what is right. You are Arthur Pendragon. No matter what happens today, I know for a fact that your story will be told. But it's up to you what legacy you leave behind. An epitaph or a legend.

Arthur: But who will stand with me?

Galahad: Galahad, stands with his king!

The knights and earthbenders arrive with their horses.

Lancelot: I will stand with you!

Toph: These are dark times. So we must all jump in together to save humanity.

Steve: Sir Steve's got your back, King-o!

Douxie: And I.

Archie: You'll need air support.

YN: If we're going down, then let's make something that's worth to remember. I'm in.

Arthur nods and put his crown back on.

Arthur: Then let Camelot be remembered as the warriors we were born.

Everyone: Huzzah!

Time skip

Jim and Claire found Callista who's trying to get rid of the amulet but to no avail. She doubt's about herself being worthy of being a Trollhunter. But Jim does not because he also took that path of doubt and yet he press onward. Not because he's not afraid of it, because he has people who are counting on him. Now she should believe in herself. With that, they leave and the king arrives to the killahead bridge where he meets Gunmar and his army.

Gunmar: One king cannot stand against an army, Arthur!

The wizards then arrives.

Douxie: It's a good thing he has an army!

The Trollhunters arrive before the rest of the army of Camelot and earthbenders arrive as well.

Gummar: Perfect! More meat for my troops. Berserkers, tenderize them!

Some of the gumm-gumms roll down and turn into stones when they roll down to the sunlight to form a cannonball to destroy the humans defenses.

Archie: Living cannonballs! Look alive!

Toph: Counter defenses!

The earthbenders form a thick wall to stop the rolling cannonballs.

Merlin: We must hold Killahead Bridge, no matter what nightmares Gunmar throws at us.

Jim: (Whispers.) Come on, Cal. We need you.

Gunmar: Arthur, I can smell your fear!

Gumm-Gumm: It's leaking out of his pantaloons!

The gumm-gumms laugh at the joke.

Gunmar: Prepare to be crushed!

Galahad: Today's as good as any to die. Though I never learned to read.

YN: Just wish I had another moment with Aja before I die.

Steve: Same here. I'll miss Pepperjack.

Arthur: Knights of the Round Table, our battle cry will shake the heavens and awake the old gods to witness. Today, we say "no more" to fear and darkness! For Camelot and glory!

They all cheers.

Douxie: I know the Trollhunter isn't here, but we are! Champions! And when I get us all home, brunch on me! For Camelot!

Everyone For Camelot!

Steve: USA! US-- uh Cam-e-lot! Cam-e-lot!

Merlin: Hisirdoux, our fates may be uncertain, but there's one thing I am sure of. I chose you well.

Douxie: Let's show these blokes the power of wizards!

Toph: If we die, then at least we'll go down fighting for what's world fighting for.

YN: I am honored to fight with another earthbender.

Unbeknownst to anyone the arcane order are watching from a far distance.

Skrael: And so the battle begins

Bellroc: And the reign of humanity ends.

Arthur: For Camelot!

The armies charge at each other and the battle of the killahead bridge has begun.