Play level 22, "All For One". You only need to save one spirit. Select the bottom right spirit and have it blow directly upwards. Next, have the spirit above it dig down when it is directly on top. This will open a passage for the spirit you are going to save to fly directly to the top of the level. Select the top left spirit and have it blow up and to the right. This will help guide the spirit you want to save away from the spikes and into the exit.