Cavern Crasher

"The Cavern Crasher is a scavenging Mystery Class dragon. It's known for pushing dragons out of their homes and taking over."

- Fishlegs reading from the dragon cards

The Cavern Crasher is a flightless Mystery Class dragon that first appeared in Dragons: Race to the Edge.

Official Description
"The Cavern Crasher flings flammable mucus and scurries across underground catacombs in search of its favorite food: Firecomb! Single-minded and voracious, the Cavern Crasher may lack wings, but its body has adapted to survive beneath the earth. With its reinforced beak and claws, this dragon climbs rock walls and hangs upside-down from stalactites. But the Cavern Crasher's most dangerous feature, by far, is its ability to excrete and eject slick mucus from the bulbous ducts on its back and then set it ablaze!"

- Dragonpedia

"With their flammable ooze and collapsible skeleton, the Cavern Crasher will push any rival Dragon out of their home and take it over."

- Dragons: Rise of Berk

Egg
Cavern Crasher eggs look like rocks, though they taper towards the top. They are red with black stripes and are covered in mucus.

Hatchling to Adult
The Cavern Crasher is a black, wingless dragon resembling a cross between a large salamander, a Gila monster, and a shell-less turtle. Cavern Crashers have yellow stripes that swathe across their eyes and similar bands around their limbs. They also have a hooked beak-liked mandible on their upper jaw, prominent tusks on its lower jaw and a thick, rounded tail. It has multiple bumps and craters on their back that secrete slime. Its glistening hide has an overall "slimy" appearance.

Titan Wing
Titan Wing Crashers in Dragons: Rise of Berk look similar to their younger counterparts, but have glowing crystal-like spikes on their backs. The yellow stripes are replaced with luminous light blue, lilac and teal hints.

Firepower
The Cavern Crasher is able to secrete flammable mucus from its body. It launches out the mucus from its tail or body onto other objects before igniting them with its flames. The Cavern Crasher can also set its tongue on fire. It is able to shoot out long, green blasts of fire at its enemies.

Being similar to Monstrous Nightmare gel, the flammable mucus might also have the effect of breaking down Death Song amber.

Collapsible Skeleton
"No stranger to tight spaces, the Cavern Crasher can flatten and squeeze its accordion-like body to sneak through cracks and past its enemies."

- Dragonpedia

With a collapsable skeletal structure, the Cavern Crasher is able to navigate through the tightest of wall crevasses.

Wall Scaling
The Cavern Crasher can scale cavern walls and ceilings like geckos very quickly.

Endurance and Stamina
The endurance of the Cavern Crasher is proven from its body that is able to take many attacks simultaneously, most notably from a Fireworm Queen, a Monstrous Nightmare, a Night Fury, a Hideous Zippleback, a Gronckle and a Deadly Nadder. It even came out unscathed from having multiple large rocks fall on it as a result of Hookfang firing at the cavern ceiling above it. And it was able to survive the doubled firepower of Hookfang and the Fireworm Queen, after combining their flames, at short range.

Despite its large size, the Cavern Crasher shows no lack of stamina as it fought against the Fire Queen for some time and won the fight even though it wasn't a fight the Fireworm Queen was willing to lose because it was protecting its eggs. Its high stamina also allows it to effectively search for its prey, the eggs of the Fireworm Queen, while also fighting against other dragons. Snotlout even stated this dragon wouldn't give up to get its meals. The only reason the Cavern Crasher eventually gave up a fight with the Dragon Riders and the Fireworm Queen is that its mucus was cooked off by the combined flames of Hookfang and the Fireworm Queen and found itself lacking the offensive capability to continue the pursuit.

Speed and Agility
The Cavern Crasher is proven to be a very fast dragon, as it is able to climb walls fast enough to make Astrid believe that there is more than one in the dark caves. It is also shown to be agile enough to maneuver around its surroundings.

Strength and Combat
The great strength of the Cavern Crasher is proven from its size; it is able to take on a Fireworm Queen, which causes this dragon to flee from its territory to find help; making it a powerful opponent.

Hunting
The Cavern Crasher uses its abilities to overcome larger or more numerous dragon opponents and ward them off so that it can eat their eggs.

Stealth
Since it crawls very fast, the Cavern Crasher has great stealth on its side to hunt its prey easily in dark caves.

Burrowing
The Crasher has been shown to be a very fast digger, as they are able to appear out of the ground at high speed and are strong enough to burrow through rocky walls.

Senses
The Cavern Crasher is shown to have an acute sense of hearing as it was able to hear baby Fireworms screaming.

Intelligence
It has been seen to be smart enough to leave a trail of the mucus in the entrance of the Fireworm Queen's nest and to use it later against the Riders and their dragons by igniting it.

Swimming
It's quite possible like other dragons, the Cavern Crasher can swim since Fireworm island is surrounded by the sea. Since the Dragon Riders got to the island by air, this dragon needs to swim to the island due to it being a flightless species.

Behavior and Personality
Described to be cruel and cunning, the Cavern Crasher raids other dragons' nest mercilessly, consuming their offspring and eggs. This dragon is exceptionally smart and deceiving, outsmarting several of its opponents and is more than relentless in getting its meal.

Weaknesses
This dragon's defenses can be overcome by blasts of fire that are large or powerful enough to cook its mucus away, leaving it vulnerable.

Season 3
In the episode "Crash Course", a Cavern Crasher raided a Fireworm's nest for its eggs. The Fireworm Queen sought help from the gang and when they arrived, they attempt to catch it with bolas. The dragon quickly retaliates by spraying mucus on them and setting it on fire. While Snotlout and the Queen split from the herd to save the baby Fireworms, the rest of the gang fight the Cavern Crasher. The Cavern Crasher safely eludes them all with its skills and make it to the hive. Over there, the dragons attempt to combine their firepower to incinerate it, but the Cavern Crasher survives. Fortunately, its mucus had been cooked and it have runned out of fire. The Cavern Crasher quickly flees.

Season 6
After finding out that the Dragon Flyers are breeding Singetails in "Family Matters", Fishlegs and Meatlug lure the same Cavern Crasher from "Crash Course" with a Singetail egg to help the other Dragon Riders escape the island after being cornered in a cave. When the Crasher has tunneled another exit, Snotlout and Hookfang lure the dragon away from the island.

Dragons: Rise of Berk
The Cavern Crasher also appeared as a Rare dragon in Dragons: Rise of Berk, along with its Titan Wing form and four individuals: Slimeslinger, Firecomb Crasher, Slimeball and the Exotic Cavern Crasher.

School of Dragons
While the Cavern Crasher is not (yet) a playable dragon in this game, it is mentioned in one Stable Quest named "Cavern Hunt".

"A Cavern Crasher has made its nest near the School, and will endanger the Hatchery if it isn't chased away from the island!"

Trivia

 * The Cavern Crasher is the third confirmed flightless dragon, after the Speed Stinger and the Bewilderbeast.
 * It is also the only one of the three that can breathe fire.
 * Though it is the third known flightless dragon, it is the first dragon to have no wings, followed by the Silkspanner.
 * The Cavern Crasher's ability to squeeze its body through tight spaces is similar to that of the Raptortongue from the books. It might also be inspired by the myths of rats and mice possessing collapsible skeletons.
 * The green fire of the Cavern Crasher is similar to the green atomic breath of Zilla Jr. from Godzilla: The Series as well as Dragon Maleficent from Sleeping Beauty.
 * The Cavern Crasher appears to be heavily inspired by fire salamanders or tiger salamanders. Fire salamanders are amphibians with yellow and black markings similar to the dragon. The Cavern Crasher's ability to produce flammable mucus may be based on the myth that the coat of mucus on the body of fire salamanders protected them from being harmed by fire. It also resembles a Gila monster or an alligator snapping turtle without a shell.
 * The knobby bumps on its back that ooze flammable mucus are reminiscent of poison glands found on the skin of many amphibians, as well as the egg pouches of Surinam toads.
 * They also greatly resemble the Pocket Salamander from The Elder Scrolls.
 * The Cavern Crasher's ability to fling flammable mucus may have been influenced by the spiny-tailed geckos' ability to squirt noxious fluid from their tails, and this fluid can become very flammable when mixed with ammonia.
 * The Cavern Crasher's behavior and abilities could also be inspired by that of the Devil's coach horse beetle.
 * Both species can excrete fluids from certain parts of their bodies.
 * Both species are known to raid nests of other animals.
 * The Cavern Crasher is the fourth species of dragon confirmed to prey on another dragon species (Fireworms), with the others being Scauldrons (which prey on Seashockers), Changewings (which prey on Night Terrors), and the Submaripper (which preys on Scauldrons).
 * The Cavern Crasher is the fourth dragon species that can burrow, with the first being the Whispering Death, the second being the Screaming Death, and the third being the Snow Wraith.
 * However, the Cavern Crasher seems to be specialized in burrowing, as Hiccup mentions there is not much space to fly in the tunnels, which may explain why it lost its wings and gained the ability to squeeze through small openings.