Enchantix is a transformation first seen in Season 3.
In order for a fairy to earn Enchantix, she must make a major sacrifice for the well being of someone from her respective planet of origin. In this form, the powers of a fairy are very stronger, acquire the ability to be miniaturized and can break dark spells with fairy dust, which is contained inside a collar.
Fairies not always has to go to their respective planets to get their Enchantix, this was seen when Stella protected her father from a dragon in Eraklyon. Musa when she saved the Princess Galatea from a fire in Alfea and Tecna when she closed the portal of the Omega Dimension kingdom of Andros, but whose instability was a danger to a great part of the magical dimension, including her home planet Zenith.
Bloom was the exception to the rule. By believing in her power to overcome evil, learn to focus her energy with the sorceress Mya on Pyros and put aside the desire for revenge and anger that she was carrying. Bloom could transform by herself through force of will, also thanks that she found Buddy, her inner dragon, thus her Enchantix was not complete. Bloom earned her complete Enchantix in the 1st movie.