This is the LEAST achievement of the SUPER7 achievements that you should worry about.
1. complete Seven Squared achievement
that anyways requires you to complete 49 cards
2. Complete other specific achievements that require to complete a card eachBlock-Buster achievementToy Box achievement
3. Complete the last 26 cards simultaneously with High-Roller achievement
in order to reach level 10.
It's basically playing new cards that haven't been played in order to receive 5,200XP for completing them each instead of just 200XP for completing played cards each.