
First, because candies fall through the teleporters and the Evil Spawners in the center are hit by matches formed by cascades. With only 4 colors on the board, there are a lot of cascades!
Second, you need them to make the Color Bomb/Candy Bomb combination. This combo will give you massive points, so concentrate on making Color Bombs and match them with the color of the Candy Bombs.
Watch the video below, it was a fun level for me: