Something seems to be wrong about the Emissary of Spades (encountered at 4-4). He can Block 51 without any card requirements (meaning stunning doesn't keep him from blocking). Despite all the damage sponging, I got him down to 20% health, but the Amplify mechanic meant he cleanly 2-shotted me. That can't be right for a normal enemy encounter - I think that move needs something like "2 spades" as a requirement, or at the very least "1 card" as a cost.
The game really could use some sort of card library - a collection of items seen, as well as a bestiary. It would give a good sense of progression beyond runs. Accessing the casino games from the main menu would also offer a nice change of pace.
The different roster skins should be more than cosmetic, they ought to have different boni attached to them. Some suggestions: prolonged scroll/shadow cloak duration, 10% or so coin bonus, greater jump height (for the city level), longer combo cooldown, improved multiplier and so on. Since coin farming is tediously slow, add a cumulatively rising coin payout for crashing gates (about 50 for the first, 75/100 f0r the second and so on).
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