The luck stat contributes towards the random prizes that are seen on the homepage of the game. The more luck you have, the more likely you are to obtain a prize after completing a mission! Luck also improves your chances of winning in Battle of the Bands
Luck can be temporarily gained from four leaf clovers. These have a chance to be obtained after completing a mission. They don't last for very long though!
Luck can also be permanently gained through various cards:
Instruments are an important item for the later zones in Rising Star as they allow you to form your band. Also, the more instruments you have, the better you will perform in Battle of the Bands! They also give you luck!
There are three tiers of instruments in Rising Star: Cheap, Mid Range and Rare/Epic. Each type of instrument (Guitar, Bass, Mic, Keyboard and Drum Kit) has Cheap and Mid Range variants, with some having rare or epic variants as well. There are also Cheap Decks for a bedroom DJ! Cheap instruments give +1 luck, while Mid Range ones give +10 luck.
The two Rare cards are Congas and Vintage Synths granting 50 extra luck and the Epic Double Neck Guitar a whopping 100 luck!
Like the other stats, many rare or higher cards give luck too.