There are ripples at the foot of Rainbow Island. What's the special effect?

That's a special effect of combining professional elf stone with constellation cloak. Professional elvish stones can be copied and knocked off quickly (I recommend unexpectedly fast, after all, the probability is high). You can buy a constellation cloak in the mall, but the mall has no attributes. If you buy from a player, pay 9 or double 9. If not, you might as well go to the mall and buy your own map.