Luxor 2

It's best to wait until you have a 'colour cloud' power up to attempt this, and then fire your powered-up ball into the middle of some different coloured balls stuck inbetween long rows of others of the same colour.

That could be confusing, so I'll explain using this diagram.

GGGGGGRBROBGGGG

Fire your powered-up ball into the 2nd Red ball and they'll all turn green. Now wait for a green ball and fire it into those other greens to get the achievement.

Well as you might know once there is 3 more balls together it then blows up and dissapears. so you either need to start with 11-12 balls which will happen every so often or kinda set it up in which 12 balls will come together.

RRRROORRRRRRRR

If something like this occurs just blow up the middle two and the other ones will come together.

Any Questions, Just send me a message
GT: xGodDogx

For me , I just went to practice mode and kept playing 1-1 and 1-2 over and over again. Eventually, a link of 12 will come out, or you will be able to make one using the methods above.

The first few levels, especialy 1-1 "Village on the Nile", have long sequences of same-colored balls. Simply bring two of them together by making combos between them to match 12 at once. For example, if you see a sequence like RRRRRRYYYGGRRRRRR, match the yellow and green groups in the middle first.

The following powerups can be helpful too:
Color Cloud turns all balls inside a limited distance to the specified color. Aim at an inside corner for better coverage.
Wild Ball counts as any color for matching purposes. Aim it between two long sequences of same-colored balls to match them both.