Winx Club (2004)

S2E24 Desperately Seeking Bloom

Bloom finds herself imprisoned by Darkar, who intends to merge Dragon Fire with Shadow Fire to unlock the portal to Realix. The Winx Club, along with the Heroes, races to Shadowhaunt to save her. Thankfully, Amentia and her guards offer their assistance, but they arrive just in time to discover that Darkar has already corrupted Bloom, transforming her into a force of darkness!