Kraken are a sea creature that normally remains elusive and solitary, who travel in the deepest oceans. No one knows how big the largest ones can become. The few that have been caught tend to measure in the tens of metres in length, but sailors have reported spotting larger ones.
Kraken appear to be similar to squid and octopii in appearance, having a central body with many suckered tentacles surrounding a hard beak. In fact, a squid is often mistaken to be a kraken. The way to tell them apart is by the glow; A Kraken will magically glow when on the attack, using its innate magics to increase its speed and strength.
This innate magic makes the Kraken greatly sought after, but it dissipates quickly after the creature's death. Magical preservation means are usually the only way to keep the innate magic around long enough to reach interested mages and wizards.