Thanks for your comment and thorough review! ☺️
The pierce + double shot is indeed overpowered but it cost you 40 health in the same should to buy. For me it looks like a win-more kinda thing, if you had 40 beats to spare in the second shop you would have won either way. I'll let someone who was on game design elaborate more if I'm mistaken!
Edit : didn't see maxime already addressed this point :D
Thanks again for playing your game and I hope you enjoyed it!