Fire Types

In both Book and film version of How To Train Your Dragon many of the dragons have unique types of breath weapons. These differences make the dragons attacks much more unique. Here are some examples.

Night Fury
The Night Fury's fire is an explosive semi-solid mass of acetylene-oxygen flames. The flames are purple mixed with bluish-white in color. When it hits a target it explodes on impact. The explosion is made up of a bluish-purple gaseous ring and a huge ball of fire at the center. The burst of flame will explode even if it does not hit a target (as can be seen when Hiccup is riding Toothless for the first successful test drive). A Night Fury's flame can also be sustained for long periods of time, similiar to a blow-torch. This is shown only when Toothless is preparing to rest or sleep, which he uses a sustained blowtorch-like flame to warm an area before resting there. Contrary to what the Vikings claim, Night Fury's fire probably burns hotter than the Deadly Nadder's. This is because acetylene and oxygen can burn at around 6,500 degrees fahrenheit (hot enough to melt Tungsten, which has the highest melting point of all metals), while magnesium burns at around 5,600 degrees fahrenheit. Though since no one has been able to capture, much less study a Night Fury this can be considered obsolete information..

Toothless' acetylene-oxygen flame is actually ionized enough to become plasmoid (at least according to Hiccup). This would explain why it explodes on contact. Plasma works almost like a cross betwene a liquid and a gas. Interestingly it can exist a many temperatures (not just extreme heat). Night Fury fire seems to carry this through. Toothless has been seen to use smaller blasts just to blow things over or illuminate dark areas. These blasts do not seem to be as hot as his others, and it is very likely that he can control the relative strength and heat of his blasts. Toothless seems to refrain from using the higher temperature, more lethal blasts against enemies when he can help it. This is almost certainly due to Hiccup's influence on him.

Hideous Zippleback
The Hideous Zippleback has one of the most interesting ways of producing fire. Unlike most other dragon who breath in a flammable gas and then ignite it while exhaling, the Zippleback has one head that produces the gas and exhales it without igniting it. It is unknown what chemicals make up this gas, but it is known that it has an explosive effect and produces a great deal of smoke. These Chemicals produce a huge, flowing, green fog. The fog is said to have a noxtious scent (this suggests it may be metabolic gas, like flatulance). It is bad enough to make anyone who breaths it in feel extremely nauseous. The gas, after being exhaled, is then lit by a spark from the other head.

Deadly Nadder
The Deadly Nadder's fire is very hot. It is said to be able to melt steel and turn a Viking into ash in seconds. The Nadder's fire is made up of magnesium. This results in the fire burning in a brilliant bright color with sparks flying off of it. Magnesium burns at around 5,600 degrees fahrenheit. The Nadder seems to be able to breath fire without taking a deep, open mouthed to inhale. It is capable of sustaining its fire for long periods. However, due to its blindspot, they prefer to use their tail spines instead of fire.

Monstrous Nightmare
The Monstrous Nightmare has some of the most dangerous fire. It is very similar to napalm or kerosene gel, so it is likely that unlike other dragons who make fire with gas, they produce a flammable liquid and ignite it. When the Monstrous Nightmare breathes fire it is a sticky napalm-like burning liquid. This fire is very destructive as it flows over houses and fields, but it actually doesn't seem to really be that hot as Hiccup is able to stand relatively close to it when he is being attacked by this fire.

Because the fire is sticky, the Monstrous Nightmare often coats itself in it - another possible sign that the fire isn't all that hot, as Hookfang's fire coat causes discomfort but no real damage to people sitting on even a full burn. It should be noted that when using a their firepower they are always seen spewing it over a target as oppose to blasting it, or when they blast it it is usually at short-range.

Gronckle
The Grockle's fire is a very unusual one. These dragons first eat rocks, which melts in their stomach, and then fires them as balls of molten lava. These lava blasts are shot out with great force and can cause serious damage once they hit their target. Attempting to block one of these blasts with a shield would probably not work. Because the blasts have a fairly solid base the blast will plow through obstacles until it hits something hard enough to splatter the lava ball. This is seen in Riders of Berk episode  'Alvin and The Outcasts' when the dragons attack the outcasts.

Terrible Terror
The Terrible Terror's fire were described more as sniper bullets than flamethrowers. Their fire projects in long concentrated streams with deadly precision. Gobber says that you know when their about to strike when you hear a little hissing sound.

Red Death
The Red Death is a tremendous dragon, and its fire is equally massive. One blast incinerates the entire Berk fleet. It is a billowing orange flame, and it has more ash than most other dragon flames. It creates large amounts of black smoke. The Red Death inhales deeply before shooting fire. Directly after being ejected, the fire is a purple hue, but it quickly turns to orange. The fire in the film can go over half a mile according to The Art of How to Train Your Dragon.

Grapple Grounder
The Grapple Grounder can shoot a light-blue ball, possibly of electricity or plasma or the sort. It can shoot multiple of the blue orbs at a time, but at a sacrifice of size. The balls have a somewhat magnetic field, drawing towards larger objects than it (ie, opponents or victims), however the more decreased the size the stronger the force is. This information could also infer it might be electric. If a Grapple Grounder takes a deep enough breath, or charges it long enough, the fire will come out as a big blackish sphere that explodes impressively upon impact, almost fatal.

Whispering Death
The Whispering Death's fire takes the shape of rings of yellow fire and smoke. It also has the ability to spit normal fire as seen when Whispering Deaths attack Bork and his girlfriend from below.

Snaptrapper
Snaptrappers are known to spit acid and sweet-smelling, chocolate-scented gas instead of breathing fire.

Timberjack
The Timberjack spits a fire similar to the Monstrous Nightmare's. It is slightly more sticky and globulous. It resembles burning embers and create beautiful glowing sparks. The Timberjack can be seen warming itself with its own fire during the Book of Dragons short.

Scauldron
The Scaldron's "fire" is not fire and therefore unusual. These dragons first swallow a gallons of water, heat it in their stomach, and then fires the water in a scalding jet at its prey/victim. The dragon gets its name from this ability. The water it spits is extremely hot and will usually finish off it's prey/victim with a single shot. Gobber claims it will melt the flesh right off your bones.

Thunder Drum
Instead of breathing fire, the Thunder Drum delivers a sonic blast that is deadly at close range. This sea dragon has a lot of, uh... spunk. The Thunder Drum lets out sonic blasts so loud it's been known to shatter glass and crack teeth. The blast ripples through the air and can push obstacles and enemies back at great speed. It is, as mentioned earlier, really only severely dangerous at close range, but it remains a devastating attack all the same. At the very least, a normal person's eardrums run the risk of rupturing. It has proven strong enough to break off the main mast of a ship and send a horde of wild boars flying. It is theoretically possible that the sonic roar would be more effective against targets that are underwater, since sound travels better through water. According to the legends, the Thunder Drum gets this power from Thor himself. It is capable of delivering a thunderous sonic blast that can be heard for miles. Thunder Drum babies hatch from their shells by making a sky-rattling sonic boom. Their sonic roar is even capable of reflecting small projectiles making it both a defensive and offensive weapon. Some dragons seem to be immune to its roar or only slightly affected by it such as the Whispering Death. However, by focusing its sound into a more concentrated form, the Thunder Drum can release a sonic blast than can do more physical damage. As shown with Stoick's Dragon Thornado, this can either knock down juvenile Whispering Deaths, or even briefly stun a Screaming Death.

Changewing
Their acid is green, gurgling, sticky, and melts through most substances. The Changewing can spray large amounts of acid at a time. It is highly dangerous and is shown to eat through huge wooden trees in seconds, however it cannot destroy metal. The dragon appears to be mostly immune to its own acid as it can walk through it without showing any signs of pain. But in the short Book of Dragons, they breath fire.

Boneknapper
The Boneknapper has a fairly regular looking fire. Similar to the Red Death, this dragon takes a deep breath before breathing a huge flowing stream of ashy fire. It does not appear to have extremely hot fire since the kids are able to survive very close to the fire during the Legend of the Boneknapper short. Also the fire keeps coming up and down in waves.

Skrill
The Skrill spits an electrical white fire as its body crackles with static electricity. As soon as the dragon begins to breathe its fire-like breath, the electricity arches through its mouth and sparks along the gasses that form the body of the blast. It is one of the most unique types of blasts since it contains both an extremely hot fire and an electrical current. It also contains ozone.

Typhoomerang
The Typhoomerang flies in a scorching tornado of whirling fire. It is capable of creating a huge whirling burnmark with its fire. The fire also acts like a fertilizer, because once the plants are burned by the fire, they will regrow and become more fertile.

Smothering Smokebreath
The Smothering Smokebreath breathes fire and smoke.

Fire
The Smothering Smokebreath has a very hot fire. The fire is hot enough to meld metal together in order to build its nest, much like a Blowtorch can. However, the fire has not been seen being used in combat; perhaps this is because it lacks the force of other dragons' firebreath, as the flames almost seem to be running out of its mouth like a river instead of being expelled like a geyser. As well, it seems to disperse at a short distance.

Smoke
The Smothering Smokebreath emits large amounts of smoke from its mouth to create a thick cloud of smoky fog to hide itself. They are often mistaken for ghosts and other supernatural creatures, such as a "Fog Monster". According to the Riders of Berk DVD extra, "Dragon Tracker," the smoke is emitted from their skin much like the Monstrous Nightmare's fire jacket.

Screaming Death
The Screaming Death's fireballs can be launched either one at a time, or in rapid succession, much like a machine gun. Every time it launches a fireball, the frill on the Screaming Death's head flashes with flames. Alone, these fireballs are also shown to be extremely powerful, as one of them was able to obliterate a tower in Berk in one shot.

Flightmare
The Flightmare shoots glowing blue mist that paralyzes its victims just long enough for it to finish them off. Rather than freezing a target immediately, the initial paralysis seems to be caused by "stiffening" the skin, making it harder for the muscles to work. As the skin absorbs the mist, the muscles themselves are paralyzed. The victims appear "shiny" until the mist wears off.

Fireworm
Like the Monstrous Nightmare, they are capable of setting themselves on fire and glow in the dark at the same time. The fire that they emit burns hotter than the sun, which means that the Fireworm's flames are as hot or hotter than the Deadly Nadder's Magnesium fire. The tiny Fireworms are not shown to have any fire breaths.

Queen
The Fireworm Queen is capable of breathing streams of hot fire that spews out small fireworks.

Speed Stinger
According to the statistics image, the Speed Stinger does not have any fire or ranged attacks except for its venomous tail that can temporarily paralyze its victim.

Deadly Nadder and Monstrous Nightmare
In Heather Report Part II, Astrid and Snotlout combined the attacks of their dragons. Hookfang would set himself on fire (everything except his head and part of his neck to avoid toasting his rider, apparently) and fly across Stormfly's path right as she launched her spikes. When timed correctly, the spikes would set on fire as they passed through the edges of the fire jacket, making it even more important to get out of the way.

Thunder Drum and Night Fury
In Live and Let Fly, Hiccup and Stoick fought against an armada of outcast-ships, and Hiccup noticed that Toothless's plasma burst combined with Thornado's sonic roar to make a fireworks display of purple sparks. He called it a plasma scattershot.

Skrill and Night Fury
In View to a Skrill Part I and II Toothless fires a Plasma Blast at the Wild Skrill and then the Skrill fires back with its lightning, creating a purple plasma lightning explosion.