Purple Wisp

The Purple Wisp appears in Sonic Colors, exclusive to the Wii version.

Appearance
Being a Wisp corrupted by Dr. Eggman's evil control, the Purple Wisp has a more menacing look than the other Wisps. It has three tentacles stemming from its pointed head, which only has a jack-o-lantern style mouth on it. It is the only Wisp not to have eyes, besides the DS-exclusive Violet Wisp. When Sonic absorbs it, he transforms into a giant Sonic head. Unlike other transformations in the game, it looks more twisted, more vile, and more feral than any of the transformations, topping it off with a serrated mouth.

Ability
It gives Sonic the Purple Frenzy Color Power, which allows him to become a berserk chomper that eats anything in its way, including enemies and certain obstacles. It will also increase in size as long as it continues to eat. In this form, Sonic causes as much destruction as possible, but his strong will bends it to a good use.

The Purple Wisp is not actually a Wisp, but a Nega Wisp, a Wisp whose Hyper-go-on power has been drained by Dr. Eggman. This explains why the Purple Frenzy is fueled by consumption.

Trivia

 * In the game manual and according to Tails, it is actually called the "Nega Wisp". The Violet Wisp is the Nega Wisp of the DS version.
 * The Purple Frenzy is first used by Sonic in Asteroid Coaster Act 1.
 * The Purple Wisp (Nega Wisp) is often referred to as the Purple Frenzy. The Purple Wisp is the name of the Wisp, but the Purple Frenzy is Sonic using the color power of the Purple Wisp.
 * The Purple Frenzy is the only Wisp that is not featured in Eggman's Sonic Simulator.
 * Upon the Purple Frenzy reaching a certain size, the player will be able to pull in rings.
 * If the Purple Frenzy doesn't eat anything for a short while, it'll start hopping and barking like a dog while moving.
 * In the final pre-credits cutscene of Sonic Colors, it is shown that the other breeds of Wisps are somehow able to restore a Purple Wisp's Hyper-go-on power, transforming it back into its original form.
 * When using the Purple Wisp, there is a blur that appears along the sides of the screen.