Not sure if you figure this out yet or not. But if you have any color match of 5/6 you get a rotor, 7/8 you get the tnt, and 9+ you get the cube thing that gets rid of whatever color cube you used to create it unless it is next to another power up then it creates a ton of those.

I am on level 676 and stuck. Just wanted to add a note as I have been in a few of the star tournaments so I think it is all levels. It feels like I have seen it pop up for awhile now, but it is all just a blur. LOL!