Invisible Joker should be Uncommon, not Rare.
Let me explain:
Blueprint and Brainstorm are really strong because you can make them copy any joker you have right off the bat with no strings attached. Got a big Lucky Cat with x40 mult? With blueprint and brainstorm copying it you can get x64k mult. Incredibly powerful!
Invisible Joker can also end up becoming your second big Lucky Cat, but there's a caveat. It can also become any of the other less useful jokers you might have. You can't control what it ends up copying. Not only that, but you can't even get it to copy a joker right away. You have to wait two rounds. Sometimes those two rounds with basically a dead slot can be the difference between the life and death of a run. And if you want to guarantee it copying a specific powerful joker then you'll have to sell everything else you have, potentially dooming the run anyway.
My point is that Invisible isn't quite as strong as Blueprint or Brainstorm so it being the same rarity as the other two best jokers doesn't make much sense. Making Invisible uncommon would offset the issues I mentioned earlier, making it significantly more viable as you'll be more likely to encounter it in the shop again if it ends up becoming something you don't want.
Let me explain:
Blueprint and Brainstorm are really strong because you can make them copy any joker you have right off the bat with no strings attached. Got a big Lucky Cat with x40 mult? With blueprint and brainstorm copying it you can get x64k mult. Incredibly powerful!
Invisible Joker can also end up becoming your second big Lucky Cat, but there's a caveat. It can also become any of the other less useful jokers you might have. You can't control what it ends up copying. Not only that, but you can't even get it to copy a joker right away. You have to wait two rounds. Sometimes those two rounds with basically a dead slot can be the difference between the life and death of a run. And if you want to guarantee it copying a specific powerful joker then you'll have to sell everything else you have, potentially dooming the run anyway.
My point is that Invisible isn't quite as strong as Blueprint or Brainstorm so it being the same rarity as the other two best jokers doesn't make much sense. Making Invisible uncommon would offset the issues I mentioned earlier, making it significantly more viable as you'll be more likely to encounter it in the shop again if it ends up becoming something you don't want.