Layla
She healed the mermaid queen Ligea instead of herself.
Stella
She used up all of her Winx energy to rescue her father King Radius from being attacked by the dragon.
Musa
Saving Princess Galatea from her planet Melody from perishing in the fire.
Flora
Rescuing her little sister Miele from drowning in a poisoned river.
Tecna
Sacrificing herself to close the portal to the Omega Dimension.
Bloom
Incomplete way: Focusing her energy through challenges on Pyros.
Complete way: With Sky's help, destroyed Mandragora and saved Domino. (1st Movie)