Since we can search cards by its rarity.
I would also like to search cards according to their Stars/level. Would help alot for deck formation.
e.g if i would search for a 2* in for Nightmare i would get a list of Mawpin, Bill, Artus, Crunchy etc 0xp and full.
Or just sort the cards by max level? Since that would be easier to implement under the (surprisingly) sort option.