If there is a trick for cards then you can give it a try!
In Crossover 21, you have to tactically match smart cards to achieve both vertical and horizontal magic. So you need to complete both row and column totals to 21. If you exceed 21, the fields of the cards in the row and column will be disabled. To open the closed areas, you need to complete the column with a card next to the closed area to 21. Use helpful Power-Ups that give you a smooth progression and try to earn as many points as you can!
The further you go, the harder it gets!