Limbo

Limbo is a place introduced in Season 7.

Overview
Limbo is a dimension that exists outside of time and can be used as a prison. Portals to Limbo can generate limbs and pull their target inside, ensuring that they cannot escape.

Season 7
In "The Power of the Fairy Animals," the Winx use the Stones of Memories to open the portal to Limbo. When the portal opens, the realm itself acts consciously as it extends limbs and captures the Trix.

Season 8
In "Valtor's Shadow," Valtor frees the Trix from this time-space prison and asks them for help.

In "Mission for the Prime Stars," the Winx learn that Valtor freed the Trix from Limbo.

Trivia

 * "Limbo" is the name for two locations in the afterlife according to Roman Catholicism:
 * The Limbo of the Patriarchs is where the souls of people who died in the friendship of God despite their sins would wait for redemption by Jesus Christ to make it possible for them to enter Heaven.
 * The Limbo of the Infants is the destination of the souls of unbaptized children who died in infancy, and were therefore too young to have committed sins but were not free from the Original Sin.
 * By extension, the term Limbo has been used to describe an intermediate place or situation of neglect or oblivion which results in unresolved status, delay or deadlock.