User blog comment:Aphrodite Sweetheart/Official Winx Club WOW and 4th movie discussion blog/@comment-2056915-20160622064512

The transformation for World of Winx is confirmed to be "Dreamix".

Source: Michael's Winx Club

Related images: http://www.michaelsfavorites2.com/winxclub2016/michaelswinxclub_no_stealing_newspage2016_1228.jpg (I do not upload it because it belongs to Michael's Winx Club)