Special Blocks such as Rockets, Bombs, Candies can be created by combining blocks, purchasing pre-game booster items, or participating in various contents.
If there are more than 1 Special Blocks adjacent to one another, once used the explsion will radiate from the center of the Speical Blocks.

Rocket : combine 5 or 6 same colored blocks
Bomb : combine 7 or 8 same colored blocks
Candy : combine 9 or more same colored blocks

You can combine Special Blocks to make Combo Blocks and clear larger areas!