The story began with Hiccup narrating an old legend.
"A long time ago, legends spoke of an incredibly dangerous and powerful dragon. A dragon that most Vikings today don't even think exist. It's called the Mutantlator. It's a monstrous dragon that's said to have the abilities of every dragon in existence, both discovered and undiscovered. However, it does have it's own unique ability. It can combine the blasts of two different dragons into one powerful blast with the combinations being seemingly endless endless. Bork the Bold mentioned the Mutantlator in his notes, describing it in his words as the Dragon of Death. The reason for that? No one has ever lived to describe what it looked like since, much like the Night Fury, it never stole food, never showed itself and never missed a shot. But it also…never leaves anyone that sees it alive. No one has ever seen the Mutantlator, except for a few".
One day, Hiccup, Toothless and the other dragon riders were off rescuing dragons from dragon hunters when they saw the dragon hunters getting lectured by someone who looked like their commander.
"OK, remember. There is no point in trying to shoot it down. If you hear it, get to cover and stay hidden until you're sure it's gone" he said.
"Has anyone ever tried to shoot it down" a dragon hunter asked him.
"No, because of multiple reasons. It's as fast as a lightning bolt and it can stay camouflaged while flying, so it's basically impossible to hit it" he replied.
"Is there even proof that the Mutantlator actually exists" another dragon hunter asked him.
That got the dragon riders attention, especially Hiccup, his mother, Valka, and Fishlegs.
"The Mutantlator? What's that" Snotlout asked.
"I don't know, but it sounds cool" Tuffnut replied.
"It's an old legend" said Hiccup.
"Supposedly, it's about a legendary dragon that's said to have the abilities of every dragon to ever exist, both discovered and undiscovered" said Valka.
"Woah" the twins uttered in unison.
Meanwhile Astrid and Snotlout were speechless.
"But, unfortunately there isn't any proof that it actually exists and most Vikings think that it's just a dragon that someone made up" said Fishlegs.
"Awe" the twins uttered.
"Anyways, everyone get ready" said Hiccup.
As they were all getting ready to strike, they heard what sounded like a Night Fury charging up a plasma blast.
"MUTANTLATOR" a dragon hunter shouted.
"Get down" the commanded shouted.
They all ducked behind barrels and dragon cages.
BOOM!
A ship exploded as a large black shadow moved past the explosion at lightning speed. Hiccup and the others were just in awe. Snotlout was speechless and the twins were mesmerized while Hiccup, Toothless and the others were in shock of what they just saw. A legendary dragon, once thought to be a joke, was actually real. Just then, they all heard the sound of another shot charging up.
"Here it comes again" said Astrid.
"Brace yourselves and keep your eyes open" said Hiccup.
BOOM!
Another ship exploded and they all saw the same large black shadow fly by again. Their gaze followed it, but it disappeared as soon as it arrived.
"I tried to follow it with my eyes, but it's so fast I can't keep up with it" said Tuffnut.
"You think? You blink and it'll be gone" said Snotlout.
Hiccup took a deep breath and sighed.
"Come on, let's get in there" he said.
They all jumped on their dragons and joined the fight. In the end, they ended up freeing all the dragons just as the third and final shot from the Mutantlator hit the last dragon hunting ship. Hookfang jumped from the explosion and Snotlout fell backwards in the water. Hookfang quickly went to go get the others as Snotlout began to swim up to the surface. Just as he was about to surface, a long black tail grabbed his arm and pulled him out of the water and onto the docks.
"Thanks, I…" Snotlout stopped talking.
Before he could finish, he looked up and was shocked and wide eyed at what he was seeing. There was a hooded figure wearing a mask, riding the legendary Mutantlator. Snotlout quickly wiped his face and got a better look at the Mutantlator. It looked like a Night Fury but stood as tall as a Monstrous Nightmare. It had 4 gigantic wings like a Stormcutter and 3 long tails that were covered in spines.
"Snotlout" Hiccup called out to him.
The masked rider and his dragon both glanced at that direction before looking back at Snotlout. The Mutantlator formed it's 3 tails into 1 big tail like a Triple Stryke, then took off high in a flash. Snotlout continued to stare up at where they left even after Hookfang came back with Hiccup, Toothless and the others.
"Snotlout, are you alright" Hiccup asked him.
He didn't respond and continued to stay silent.
"Snotlout, what happened" Astrid asked him.
"I….I saw it" he replied.
The others froze after hearing what Snotlout said.
"You saw the Mutantlator" Valka asked him.
"Y-yeah" he replied.
"W-what did it look like" Fishlegs asked him.
Snotlout quicky pointed at Toothless.
"Like him, but bigger. It had 4 massive wings like a Stormcutter and 3 tails like a Triple Stryke" he said.
The others glanced at Toothless before looking back at Snotlout.
"Woah" the twins uttered in unison.
"That's not the only thing I saw" said Snotlout.
"What, what else did you see" Hiccup asked him.
"I-it…it has a rider" he replied.
They all froze and their eyes widened.
"Yeah, I saw someone riding it. I couldn't see their face, it was covered up. After you started calling for me they both took off in an instant" said Snotlout.
"What now, Hiccup" Fishlegs asked him.
"Let's get out of here. We'll discuss the rest back home" he replied.
They all got on their dragons and were about to start flying back to Berk when Ruffnut and Tuffnut saw something on the shores of a nearby beach that made them stop Barf & Belch.
"Oh my Thor" Tuffnut uttered.
"Hey! You guys gotta see this" shouted Ruffnut.
Their dragons stopped and they turned around to see the twins flying down to the shores of a nearby beach.
"Oh, boy" said Astrid.
"I wonder what they found" Hiccup asked.
They landed and were shocked by what saw. Dragon Hunters paralyzed and partly incased in what looked like a mix between Bewilderbeast Ice and Deathsong Amber.
"Are…are they" Fishlegs was cut off.
"No, they're alive. They're just paralyzed and encased in whatever this is for good measure" said Valka.
"Something the Mutantlator can do is combine the blasts of two different dragons into one blast" said Hiccup.
"That's right" said Valka.
"Fishlegs, what can you make of this" Hiccup asked him.
Fishlegs took a closer look at the substance the dragon hunters were encased in. It was cold as ice and hard as stone.
"This substance seems to be a mix between Bewilderbeast Ice and Deathsong Amber" said Fishlegs.
"Definite sign that the Mutantlator and it's rider was here" said Hiccup.
"I still can't believe that a dragon like that is actually real" said Astrid.
"Neither can I, Astrid. Even I was in disbelief after what we all saw" said Hiccup.
They all checked to see if anything else is out of place and found several dragon cages blasted or torn open.
"All these dragon cages are wide open" said Hiccup.
"Well, it seems pretty clear to me, chief. Whoever our mystery rider is, him and that Mutantlator are on our side" said Tuffnut.
"Maybe, but we can't be entirely sure" said Hiccup.
"The Dragon Eye! If we can find SOMETHING on the Mutantlator there, it'll show us where might find it" said Fishlegs.
"Good thinking Fishlegs. Come on, let's get out of here" said Hiccup.
They all got back on their dragons and began flying back to Berk. Unbeknownst to them, their mystery rider and his Mutantlator were watching them the whole time.
"Well, well, well, it looks like we're not the only ones rescuing dragons, pall" he said.
His dragon nudged his arm and pointed his tail at the dragon riders.
"You want to follow them" he asked his dragon.
The Mutantlator smiled and nodded.
"I'd love to follow them too Lightning, but we're low on food" his rider replied.
Lightning looked down, disappointed.
"I'll tell you what, the next time we see them we'll follow them. How is that" he asked his dragon.
Lightning cheered up and nodded.
"Alright, then. Let's go back to base" said the rider.
The mystery rider then got on his dragon and flew off in the opposite direction.