Once you get the Incedio Spell, return to the main room and make sure the two pillars are down. Go into one of them and switch the flame direction so that the flames are both are on one side of the room. On the other side, use Incedio to light the pigs and Flapendo to point them up to lift the platform; then again on the other one. Run quickly to the switch by the exit. If successful the door, will be unlocked halfway. You will need to do likewise with the other side. Note: You do not have to charge at all -- this gives you a few extra needed seconds.