Rumblehorn

The Rumblehorn is a Tracker Class dragon that appeared in the movie How to Train Your Dragon 2 and in Race to the Edge.

Official Description
"A Rumblehorn’s nose knows! From the Tracker Class, it can follow the faintest scent anywhere. There is nowhere to hide from this Dragon! When a Rumblehorn doesn't want to move, it doesn't move...but when a Rumblehorn makes a charge, opponents clear out of the way!"

- Dragons: Rise of Berk

Development
The Rumblehorn was inspired by a rhinoceros, a truffle pig, a dung beetle, a jack hammer and a battle axe.

Early concept art depicted the Rumblehorn with a triple split jaw, much like the Catastrophic Quaken and Snaptrapper. This was one of Character Designer Nico Marlet's signature designs.

Physical Appearance
The Rumblehorn has relatively large wings, a wide torso, and a tail with a club-like hammer on the tip. Its most notable feature is the heavily armed front half of its body with firm armor plates on the neck and a large lower jaw, a battle axe-shaped muzzle, which is always digging in the dirt, looking for scents, and two, very sharp, elongated horns resembling those of ceratopsian dinosaurs, but lacking a beak. The Rumblehorn has a very acute sense of smell, and is determined to track down and find anything once it has picked up the scent. In total, they look like a mix of truffle pig, a rhinoceros, a battle axe, and a scarab beetle.

Titan Rumblehorns appear to have developed a shiny green armor. There are more plates to their armor and it appears harder. The horns on their head are sharper and longer, and their wings are cyan in color. Furthermore, their tail has grown more spikey tips.

Firepower


It can shoot long-ranged fire "missiles" from its mouth which initially starts out as a white-hot fireball that quickly solidifies and turns to a warmer color before it ends up in a sooty, stony material when it hits its target.

Senses
Being a Tracker Class dragon, their powerful sense of smell makes them able to find any Viking scent from long distances even if the material that worn from the water for certain period of time. They can find anything, based on scent alone.

According To Berk and Beyond, the only thing Rumblehorns cannot smell is dragonberries.

Strength
Rumblehorns are extremely strong dragons, for they are able to carry large Vikings and their weapons, as well as ramming down a sea stack while flying in full speed.

Intelligent
Rumblehorns appear to be extremely intelligent, hiding from their enemies in bushes and creating traps with their footprints. They have also been shown to attempt to chase Hiccup and the gang off Dragon's Edge by pretending to harm them, other native dragons and destroying buildings. They have even outsmarted Hiccup and the gang numerous times.

Speed and Agility
For its body size, the Rumblehorn is known to have surprising speed and agility on land, and uses this to charge as if it was a rhinoceros. As for flight it is able to spin in the air with no difficulties at all.

Disaster Detecting
This special ability was shown by Skullcrusher for his kind is able to detect any disasters that will happen a few weeks earlier up to the day it will happen as other dragons didn't sense the Tsunami.

Stealth and Camouflage
Rumblehorns are able to move silently opposite to their appearance. Their heavy body is able to hide in bushes to camouflage with their green scales.

Endurance and Stamina
With its great armor body is able to take a Singetail fire power by falling down from high altitude to the ground as it able to get back easily, as seen in Turn and Burn. The size of this dragon has no lack of stamina as proven to run in high speed to charge at its enemies and fly far distance like any other dragon.

Communication with Other Dragons
The Rumblehorn is to be able to scare other dragons into the air by either roaring or pounding the ground with its head in Crushing It.

Behavior and Personality
Rumblehorns always have their snouts to the ground, sniffing around for something edible. They can be aggressive, but are also friendly towards their riders. Their food of choice is unknown, but they are probably carnivorous. They are also highly intelligent and determined. They run like rhinoceroses. As shown by the still wild Skullcrusher, Rumblehorns can be very caring and protective of those in danger, as seen when Skullcrusher tried to warn everyone of a tidal wave heading towards Dragon's Edge. Rumblehorns seem to be solitary and elusive creatures that are rarely seen due to their keen sense of smell.

Season 1
Hiccup and the gang face a strange new dragon that has been targeting native dragons during the events of "Crushing It", and it destroying Dragon's Edge. Hiccup named it the Rumblehorn. They get Gobber to build a fortress, but to no avail. Eventually, Hiccup allows his father to help them get rid of the rouge Rumblehorn but it always outsmarts them. Back at the Edge, it attempted to attack Gobber and Toothless was told to shoot him down. Sensing that something was not right, Stoick tamed the Rumblehorn and brought the gang to the sea. Hiccup then realized that a large wave strong enough to destroy the Edge was heading their way and the Rumblehorn was trying to chase them away from the island in order to save them. Eventually, they worked together to surround the island with Gobber's fortress and the Rumblehorn, together with Stoick, collapsed a sea stack just in time to stop the wave. Stoick then keeps the Rumblehorn as Thornado's replacement and calls it Skullcrusher.

Dragons: Rise of Berk
The Rumblehorn, along with its Titan form and the individuals Skullcrusher and Seedling Rumblehorn, a subject of the Foreverwing, were made available in this game.

School of Dragons
The Rumblehorn in this game has an exclusive chest available too.

Trivia

 * The Rumblehorn shares a similar body structure with the Triceratops.
 * Its lower jaw seems to have been originally a split jaw, as evidenced of a piece of concept art.
 * The Seedling Rumblehorn slightly resembles a tortoise.