Disloyal Adversary is the eighth episode from Season 3.
Before the royal party takes place, Sky confides to the Winx girls that he plans to announce a commitment to Bloom. However, at the party, attended by royalty of Magix, Princess Diaspro tricks Sky into drinking a magical potion provided by Valtor. This resulted in Sky announcing a commitment to Diaspro instead. The Winx girls and the other Specialists are shocked by this turn of events. They quickly determined that Sky has fallen under a spell. Stella, already upset with the attendance of her stepmother and stepsister, confronts Sky. However, Sky counters with Diaspro's allegations that the Winx Club are witch agents sent by Valtor.
A pursuit of the Winx girls ensues, culminating with one of the pursuing dragons going on a rampage and nearly attacking King Radius, Stella's father. However, before it could occur, Stella places herself between her father and the dragon, which resulted in her taking damage. Rising to feet, after the dragon has been subdued, Stella's selflessness is acknowledged and she gains her Enchantix.