What do coins do?

Coins are used in-game to purchase Power-Ups before you play a song in Rock Band Blitz. These Power-Ups can help you perform better and score higher. Choosing the right Power-Ups can completely change whether you beat your opponent in a Score War, so you want to make sure you have plenty of coins to purchase the Power-ups you need. More coins can be earned by winning Score Wars, completing Goals in Rock Band World, and playing songs in Rock Band Blitz.