You're right about Battery, I definitely wanted it to only return a portion of the mana you spent. Full refunds would be flirting with disaster.
You're probably right about the swap thing too. I figured the costs involved kept it from being broken on that card at least. Being restricted to just cards in your hand helps too, so I'm not all that worried about it being OP, but you're right about it being hard to balance and even more right about design space.
Great feedback, thanks for the contest.
CotW is a method for ranking cards in increasing order of printability.
*"To YMTC it up" means to design cards that have value mostly from a design perspective. i.e. you would put them in a case under glass in your living room and visitors could remark upon the wonderful design principles, with nobody ever worring if the cards are annoying/pointless/confusing in actual play
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