do you mean the coin aka "prismatic token?" the rainbow coins can be brewed by anyone L16 or higher in Baldwin's cauldron, for 25k treasure, a silver and gold muck, a black and white slime, and five green oozes. they take four straight days to brew! Or, they can be obtained by purchasing one of Joxar's "spare inventory crates" for 80k Treasure. Each crate contains one of the prismatic tokens, and also will contain either one of the new recolor items or one of the fest items from last year or the year before. so for 80kt you get the coinn and by the estimate of folks last time, you have about a 2/3 chance of also gettign a new recolor item with it. There's also a small chance the crate adds in as a bonus one of the fesst skins frm the last two years.
What do you do with the prismatic tokens? you trade them in for one of the recolor items of your choice from Joxar's shop!
and, of course, you can also buy/trade for the prismatic tokens as well...