Superstone event is not like metin rain event which used to be. Superstone drops from the sky like normal metins, though there are 5 of them in one place, which means you need to search for them. There is no minimum/maximum level for it.
i know is not like metin rain or metin shower but those 5 in same place all have same lvl. for expl in map 1 saw only 5 stones lvl 25 in same place not lvl 15 or 10 or 5, metins u can find usualy in map1. thats why i asked about a min and max lvl for superstone.