Mega Trix

The Trix, who combined into a single entity after Lord Darkar betrayed them by sending them into Oblivion. At the end of the second season, the Trix unite their powers Gloomix and create the Mega Trix to defeat Lord Darkar. However, she failed as Winx destroyed Darkar, leaving Mega Trix alone in the Realm of Realix, screaming in rage.

It is unknown how she defused back to three Trixs as in Season 3 they were defused. It is possible that their Gloomix stopped working after Darkar (who created them) died.