With your levels going up you can unlock up to 4 slots on your experience bar that can “spawn” buffs which can give you bet multipliers, coins, experience and more. You can get increased experience during the next “x” spins, win multiplier for the next “x” spins or just get some coins if you reach the certain part during leveling. This system allows for easy integration of special collectible or event items. Buffs add a little extra to the user experience so when you spin the slots you have another goal to aim for.
To make things more rewarding the coins for example does not have a static value. The coins are based on percentage of the current level experience, so you will definitely be happy to get it. It will generally provide you with a couple of spins that will for sure help you get some more experience and with some luck maybe reach the next buff, level or get a juicy win.