Diamond
Action/Treasure - $4P
+$3
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At the start of your buy phase, you may put this on top of your deck
(Clarification: If you play this as an action, it still produces the treasure value)
So I kind of accidentally stumbled into this idea while thinking through things that would be possible with a Potion price that wouldn't be possible otherwise (like Alchemist). I initially was just trying to make a flat +$4 treasure, decided it was boring, thought about how I could do something with Alchemy's action theme, decided giving some bonus if there were actions left might work, realised that would be awkward to word, though about playing it... as an action, and suddenly realised I'd managed to stumble into an action/treasure that existed because it wanted to run on both types, not a card which was shoehorned into having both types because "wouldn't it be cool?"
And now I kind of feel two things. Firstly I feel like it works. But secondly I feel like there's some glaring flaws which I'm not seeing. I mean more than just maybe the numbers are not quite right. It could easily become +$4 or +$2 and/or go up to $5P or down to $3P. I mean it feels like there's something more problematic, but I can't quite put my finger on it.