The Cloud nine is available in the Explosive puzzle Event. To activate it, you need to pass levels without losing a life. You receive free bonuses on the field at the beginning of the next level as a reward.
Cloud nine consists of 3 stages. The more levels you pass without losses, the higher the stage and the more bonuses you will receive at the start of the level. If the level fails to pass, then the cloud bonus expires. But no worries, on the next streak of 2 wins, you will again find yourself on stage 1 of the cloud nine.
Continue your winning streak to keep it and grow!