S1·E23 The Search for the Flame

To expedite the search, the gang splits into two groups. Bloom's group finds the dragon fire first but darn, the witches are waiting for them. Luckily, the other group (Riven, Brandon, and Knut) show up as well as Ms. Griffin! To buy time, Griffin put the three witch-dropouts in temporary ""detention"", and then summons a portal to Alfea so that the remaining witches and gang can escape. Fearing that the army of decay might also enter the portal, Sky and Bloom stay behind to lead the army away.