When you match Tsum Tsum groups of at least seven (or six after using a power-up), they will leave behind a magical bubble. Tap the bubble any time afterwards and it will pop the surrounding Tsum Tsums. Save the bubble when you need to clear out space or keep your combo going. Sometimes the magical bubbles will also spawn with a power-up inside. Some are very useful, especially the one that adds two seconds to your time. Try to make as many magical bubbles as possible.