Holy Stars are usable only in the Labyrinth. The Labyrinth is a special building unlocked on your turf when you beat Skirmish 8 (the final one). This allows you to access the Labyrinth and fight the monsters inside. Instead of using energy to attack, you need 100 Holy Stars to hit a Labyrinth monster once, one energy, and any hero. It takes 10 hits to kill a monster. The prizes for killing a monster are on average very poor (on account of it being available pretty much always), however, sometimes you can win the jackpot and strike it rich. The jackpot accumulates rapidly until the lucky winner claims it as a reward for killing a Labyrinth, at which point it resets. One of the best strategies we’ve come up with is to wait until the jackpot is relatively high and dump all available Holy Stars into hitting monsters. The more monsters you can kill in quick succession, the higher your odds of getting the jackpot and winning millions of Gems. If you want to improve your rewards, you can upgrade the Labyrinth into the Elite Labyrinth by purchasing the $99.99 Labyrinth access from the store. The Elite Labyrinth follows the normal rules for hitting, but you get 11 times the rewards. The jackpot isn’t truly random, so there is usually a time of day with more winners. The three previous winners are displayed on the Labyrinth screen, so you can keep track of how often the names change. Follow the pattern of higher jackpot counts to improve your odds. However, in the end, it’s all about luck.