What are the cards and how do they work?

You start each game with a certain amount of cards, each containing one bird or spell. The amount of cards you have can be seen on the bottom left corner.

Select which bird to use next from the three visible cards. You can even get more cards by filling the Destructometer.

When the Destructometer is full, you'll get an extra card! The more stuff you destroy, the quicker the meter fills up!