S1·E31 A Place Far From Home

Shun is stuck with the female Ventus Lord, Oberus, who has summoned a child that looks like Shun's mom to battle. The child convinces Shun to play with her while the sun is still setting, which it never does. Shun must battle himself as well when he is forced to choose between going back or staying in this world with his mother. In the battle with Oberus, Shun believes that he doesn't need his friends. His belief causes Skyress to die after a great impact with Oberus. When Shun realises his mistake, a tear drops down onto Skyress' ability card, changing it, and miraclesly reviving Skyress, which evolved into Storm Skyress. In the end, when Shun chooses to return to his world, Skyress evolves to Ventus Storm Skyress.