"Domino Level Helpers" or "Level Boosters" are helpful tools that you can use during a level. They will help you undo mistakes, get more chances, or even pick the preferred tile from the board. 

Wild cards

Wild cards will allow you to pick any card from the board, it is located on the bottom right of the screen:

After you press it, the wild card will replace your current piece.

Additionally, purchasing a wild card also does not reset your combo which is really helpful for finishing streaks.

Restock

Restock appears when you run out of cards. It provides an additional three random cards which can help you finish the level.

Undo

The Undo power-up lets you undo the last tile you picked. This is helpful whenever you make a mistake, such as picking the wrong tile, or not seeing a choice on the board.

Remember, it also reduces your combo progress.