I'd like to get an item in game (cash shop is fine) that allows me to change the look of a familiar. In Some familiars are simply too hard to farm for good stats (area bosses for example), but are really fun to have around. I would love to get an item like the fusion anvil that lets me fuse the look of one familiar to the stats of another. I'd be happy to pay for this in the CS.

Now I know red cards kind of let you do this, but since Nexon clearly has no intent of releasing red cards in reboot as people have been asking for that for forever.
So at least I'd like to see this introduced as a purely cosmetic option. That way there's no pay to win element and it's just another cosmetic option in the CS.