User blog comment:BoygeyMario/Make your own Elements/@comment-30095342-20141110162145

Cluster Candies: When matched, they will transfer 10 candies at random into colour of the cluster candy (example: a green cluster candy would change 10 non-green candies at random into green candies)

Kinda similar to the glass ball(!) in Candy Crush Soda Saga.