Corner StarG 50

Corner Star G50:
Call 20 Bingo corners across multiple Bingo matches.

This is done by simply filling the 4 corners of a bingo board. Only the in match boards count. The power board will not help with this.

I suggest that if you really want this that you save up a lot of coins from the harder levels and then drop down to the easy level. Once the match ends just keep buying 5 extra balls over and over until you get all of your boards to fill the corners. I also suggest doing this at off times of the day so that the match doesn't end quickly.

It is also a good idea to use as many boards in one match as you have unlocked. More boards means more chances to fill the corners. Be careful though. Too many boards is hard to keep up with!

You can achieve Bingo in 1 of 13 ways. 5 horizontal lines, 5 vertical lines, 2 corner-to corner diagonal lines, and finally, all 4 corner spots. Once you have achieved 20 of these corner bingos, the achievement will unlock. There's obviously no way to purposely unlock this achievement through effort, so just wait and the achievement will come naturally in time.