Originally Posted by Unregistered

All my N rarity cards are Lv 100 now so what should I use my pero for? do I keep buying N wild cards and trade them for R wild cards or do I save the pero for later?

There's not much stuff to actually buy, other than N Tickets during gambit for the pink keys. I'd suggest to keep some pero in reserve (if you need to level a card quickly), but other than that, do with it whatever you like. For example, I'm currently spending mine feeding the rat voting tickets, one at a time, hoping for candy.