Skulls are special resources in Cats Empire. Skulls allow you to unlock regular and high tier boss fights.
You can start boss fights by clicking on the big boss icons on your map. Depending on the level of the boss you need normal, disco, indian, double skull or even black cards for the strongest bosses. Before starting a boss fight, you need to take out some cats while ambushing an opposing gang. There is a certain chance that skulls will fall off for you as soon as you successfully kill an enemy cat. Collect all the necessary skulls, start the boss fight and show him who's in charge!