Kraken

The ​Kraken is a special weapon in Splatoon. The Inkling Squid amiibo provides single player challenges that involve using the Kraken with a limited amount of time on different levels.

Splatoon
For a short period of time, the player changes into a monster-like squid form. It can move freely on enemy ink while leaving its own trail. Jumping into an enemy splats them instantly and the user is immune to all damage. However, Krakens are affected much more by knockback, and can still be splatted by falling into water or out of bounds.

Swim speed in Kraken form is the same as that of normal squid form. As such, its speed is affected by Swim Speed Up, Comeback, and Ninja Squid. However, Krakens are still fully visible even with Ninja Squid, so the only change is the speed reduction.

Use

 * When damaged or cornered, it is recommended to use Kraken as it grants invincibility from incoming attacks for a short time. Though it may not be the most strategically smart choice in a given situation, it would be better to use it to stay in the battle than to lose it by being splatted.
 * A Kraken can be used in a pinch to avoid being splatted by special weapons, such as an Inkstrike or Killer Wail.
 * Equipping Swim Speed Up can slightly increase the Kraken's speed, allowing the player to chase opponents more easily. Likewise, Ninja Squid slows down the Kraken's speed, so stay away from that ability.
 * Like the Bubbler, the Kraken can be used in Tower Control to sit on the tower without taking damage. However, the increased knockback can make it difficult to stay on if enemies hit from the right angle.
 * Super Jumps can still be performed as a Kraken if there is a need to escape.
 * The activation of a Kraken makes a unique noise, alerting nearby players of its presence. If this sound is heard and no teammate has used their Kraken, it may be wise to leave the area or find a place to hide.
 * Speedy targets such as the Inkbrush can be fast enough to escape the Kraken.
 * Krakens' only method of spreading ink is with the small trail behind them, so they cannot cover a large area like normal players can. Because of this, hiding in one's own ink, no matter how small the puddle, may cause the Kraken to swim right by without even noticing as long as they did not see the player before they hid.
 * Since Krakens are considered "squid forms", they can still go through grates. Opposing players can try to lure the Kraken onto a grate, making them fall and breaking their pursuit.
 * Krakens are immune to damage, but can still be splatted by falling into water or out of bounds. This can be used to one's advantage in stages with either hazard, such as Mahi-Mahi Resort.
 * In Arowana Mall, there is a grate above the water. Try luring them into falling through the grate and into the water, where they will splat themselves in the process.
 * Krakens are very vulnerable to knockback, which can be used to keep them out of melee range. Very fast weapons, such as the Aerosprays and Inkbrush, can even allow the user to simply stand in front of the Kraken and just keep shooting (or flicking) at it to keep it away, provided they have enough ink.
 * After coming out of Kraken form, there is a moment in which the player cannot use any weapons. This can be taken advantage for an easy splat if one is quick enough.

Quotes
"Activating Kraken transforms your character into a large, invincible squid for approximately six seconds. While in Kraken form, you can swim around a stage (including all inked and non-inked surfaces) leaving behind an ink trail your team can utilize to push deeper into enemy territory. You can also jump, taking out opponents in your path. You must jump to perform a lethal melee strike - simply bumping opponents will only push them around, inflicting no damage. But just like swimming in squid form, you can't cross over mesh walkways or grates while Kraken is active. If you attempt to swim over a grate, you will just fall through. This is an excellent way to avoid a pursuing enemy Kraken - rush over a grate to escape."

- Prima Guide

Splatoon 2
In Splatoon 2, as explained in Sunken Scroll 11, no special weapons from the first game return. The role of the Kraken was indirectly replaced by the Baller, in that they both deal contact damage and leave a trail of ink in their path. However, the Baller deals much less contact damage, explodes after the timer runs out or directly by the player, and can be destroyed.

Trivia

 * The early name of the Kraken was "King Squid" as was found within the files of an early version of Super Mario Maker.
 * There are no Kraken sets with Seekers, Sprinklers or Disruptors as their sub weapon.
 * Krake means "Octopus" in German, which is odd, since Inklings are based off of squids.
 * The word Kraken is based off of Krake; as such, many tales and legends recount the Kraken to be an octopus, not a squid.
 * Modding the game shows that Octolings have a unique Kraken design with curled tentacles instead of straight.
 * While the average Inkling squid form has grey eyes, Krakens' eyes are the player's ink color.