The Skrill is a medium-sized Strike Class dragon that was first mentioned in How to Train Your Dragon and first appeared in Book of Dragons. A jolt from the Strike Class, this Dragon is among the most feared Dragons. They can summon lightning to shoot electrical blasts. The spiny Skrill attacks with balls of lightning more powerful than any natural storm. Skrill eggs are round and usually come in shades of blue or purple. The color of the hatchling will match the color of the eggs. The eggs are surrounded by lightning bolts zapping around them. Its center core glows very brightly, although it is unknown if the bolts are actually electric or if they are just ornamental. The Skrill has large wings and spines on its back and tail. These spines are metallic in nature and conduct the arcing electricity that it uses as its unique firepower. The Skrill possess a crown of spikes on its head which are all about the same length. The Skrill's 'crown' can be used to steer the dragon. Skrills have three short spines on their chin. It also appears to have four shark-like gills on its neck. Its head slightly resembles that of a Thunderdrum or a Flightmare. The proportion of its head, body, and wings are quite close to that of a Flightmare's. It resembles a Night Fury in flight and almost rivals its speed, being only slightly slower. It is the size of a Deadly Nadder, but incredibly fast. This dragon has been shown to walk and run on its two legs with its wings folded.
A new model in School of Dragons was made for the Skrill, featuring the Skrill walking on two legs, instead of its original locomotion. In How to Train Your Dragon Live Spectacular, the theatrical rendition of the first movie, an animatronic Skrill is seen. It appears smaller than its animated counterpart, and more colorful, having a blue back with dark blue striping, a band of red along the sides, and a white belly. The head is also narrower and much more bird-like, with a definite beak-like mouth. However, like the animated Skrill version, the live-action version has only a pair of hindlegs and spikes around the back of its head.
The Skrill is an electrical dragon. It can absorb and store lightning's electrical energy. Using its metallic spines, it can channel lightning through its body and fire out destructive blasts through its mouth. Skrills obtain their lightning blasts from absorbing electrical charges from thunderclouds. Since the electrical charges in thunderclouds are very active, Skrills can achieve very powerful firepower. Skrills also have the ability to direct multiple bolts of lightning, striking things around themselves, making them greatly feared by Vikings. They can also store the electrical energy in their bodies and use it at a later time. Its ability to harness and store electricity gives it a static field, making your hair stand on end if you get too close. The Skrill most likely has a powerful electrolyte in its scales, which it can use to create powerful electrical charges throughout its body with static electricity, and also create a conductor for electricity to travel freely on its body. The Skrill is able to "ride" lightning bolts. It was first and only seen in "A Time to Skrill", after the Skrill was tamed and set free, it ascended upwards at hypersonic speeds through a field of lightning bolts. The Skrill was able to use the energy of lightning to accelerate very quickly and fly at hypersonic speeds. It was able to reach the clouds from the glacier it was on in less than a second, which would mean that the Skrill was traveling at least several times faster than the speed of sound. It is unknown why the Skrill only used this ability once, though it's possibly due to a limit. This move makes the Skrill far faster than any other dragon, despite the stats saying otherwise.
Skrills are able to create an electrical field, that acts similar to a force field. It does this by redirecting energy through its wings, as the electricity forms together by closing its wings together and springing its tail upwards. It then forms a small electrical field that can be used to block itself from projectiles, similar to how a Seashocker does to protect itself from predators. This was shown when Dagur was in control of the Skrill; it used this ability to block Toothless' plasma blasts in "A View to a Skrill, Part 1". The Skrill can cover its wings for extra protection against a stronger blast. However, the electrical field was seen to be strong enough to deflect some blasts from Toothless, as seen in the third time Toothless fired, the Skrill did not cover its wings. The resistance power of the electrical field cannot be determined other than it was able to deflect weak blasts. It is unknown how a much stronger blast could affect the Skrill while using the electrical field. This, however, determines that this ability is the last line of defense for the Skrill. When the Skrill was under control of Dagur, it could not dodge the blasts or accurately fire back because it was tied up on ropes. Unlike other dragons' fire attacks, where it is a single blast projectile or a stream of fire, Skrills have the ability to shoot lightning in a beam over great distances, adding more power to it and more damage to whatever is unlucky enough to get hit. It is also said to be able to direct multiple lightning bolts at once. All the electrical power it gets to fire its lightning comes directly from the clouds by natural lightning. A side effect of getting hit by the electric blast causes people to talk gibberish.
When the lightning blasts of a Skrill and the plasma blasts of a Night Fury meet head-on, a massive energetic explosion will form and can knock dragons from the sky, as displayed in "A View to a Skrill, Part 1". Skrills can fire their lightning blast with extreme precision.
According to the Cartoon Network site the Skrill's lightning blasts are equally as powerful as a Night Fury's plasma blast. Skrills have a shot limit of 4, however, while in a storm they can recharge their shots very quickly at any time they want, and they can store four blasts of lightning ready to be released. With this advantage of continuous shots, the Skrill takes a huge advantage over their shot limit by constantly firing its blasts in a quick succession. It often does not need to take good aim before firing as it can afford to miss, seeing as its shots are easily rechargeable in a thunderstorm.
Skrills are very strong for their size. The frozen specimen managed to knock away Stormfly with just one slap of its wing. It is said that the Skrill is one of the few dragons that can stand toe-to-toe against the Night Fury.
As a Strike Class dragon, the Skrill possess extreme intelligence. In "A Time to Skrill", the Skrill's intelligence was shown, as the Frozen Skrill recognized that Hiccup tried to lure him back into the glacier to freeze him, and it later tried to trap Hiccup and Toothless inside. Also, it was smart enough to follow Hiccup's trail back to Berk, and it even knew which house was Hiccup's.
The Skrill's stamina and endurance seem to be incredibly high, as the Frozen Skrill was able to emerge from hibernation, attack the Riders' dragons, go in search of food and then engage the Riders in combat with no pause in between. The Frozen Skrill was able to endure many attacks and still was able to fight. It was even seen to be able to take a plasma blast to the head and continue to battle with minor injury, where most other dragons would have been defeated at this point.
According to Dragons: Rise of Berk and Dragons: Titan Uprising, Skrill posses the ability to sing, although the sounds they produce are not always on the human taste.
The Skrill's primary weakness is water. It cannot channel electricity and loses all firepower when it is wet. If you force a Skrill to fall in the water, it will lose its upper hand. However, the Skrill can quickly regain its ability to channel lightning and electricity after getting out of the water.
The Skrill may have another weakness, as it is said in the dragon info on Hiccup's map that "they channel lightning down their metallic spines, firing it from their mouths in a shower of destructive blasts." This could mean that if one were to disable a Skrill's spines, it could take away its ability to channel lightning.
One of the most mysterious and feared species in the Dragon Manual, the Skrill is aggressive, powerful, and nearly untrainable. It appears to be almost as feared as the Night Fury, due to the Berserkers who used to harness the Skrill and use it as a weapon. This reclusive dragon is belligerent and as unpredictable as lightning strikes. It is very territorial, despite following stormy weather.
They are known to be very elusive and are distrusting towards other species of dragons and humans. Skrills tend to gravitate towards lighting storms to defend themselves against potential predators or to quickly recharge their shot limit. They are known to be very fierce and will act recklessly without thinking when released if trapped in the ice for too long.
Skrills were said to be untrainable but that was proven to be false. To tame or train a Skrill, you would need to prove to it that you are willing to risk your life in order to save the dragon. That way the Skrill can trust you. The Frozen Skrill held a grudge against Hiccup and Toothless after they trapped him in a glacier. After he broke out, he was about to harm the duo as a revenge but after Hiccup saved the Skrill from the Dragon Hunters and later freed him, the dragon finally let go of its hatred towards them and bowed, before flying off in the clouds.
The Skrill, however, has been seen to prefer being free rather than being trained like other dragons. However, when trained, the Skrill displays immense loyalty towards its trainer, willing to fight alongside him or her even in the face of death. This was demonstrated in "Triple Cross", when the Skrill refused to leave Viggo's side despite the latter instructing him to do so.