If there are two adjacent power-ups on the board, you can tap one of them to combine their power!

Combining two Rockets fires them both horizontally and vertically. 

Combining two Firecrackers creates an explosion DOUBLE the size of the original.

Combining a Rocket and a Firecracker clears out an area of the board 3-bubbles-wide horizontally and vertically. 

Combining a Rocket -- or a Firecracker -- with a Color Beam transforms every bubble of the Color Beam's color to a Rocket or a Firecracker and activates them! Whoa!