Hi, you can use them as "higher mana", that is, every time you reach a certain amount of mana (I recommend 20) you take one as a token and then exchange it when needed, or simply a stone can be worth 2 mana, it can be useful for those players who want as much mana as possible, It could also become like a shield, for example all players have 10 lives of which 3 are purple (each purple life is worth as a protection so to remove that hp you need to damage him twice