Just for the heck of it, though I suspect something like this has been done before:
Analysis Paralysis - Action - $6
Choose three of the following; your choices may be the same or different: +1 Card, +1 Action, +$1, +1 Buy, or trash one card from your hand.
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So, this is essentially a Super Pawn. It can act as a Lab, a Smithy, a Village, a Woodcutter, a Peddler, a Market Square, a Crossroads, a Silver, two of the Squire choices, or a terminal Gold. As well as a few other combinations. Obviously this is strictly better than Lab, and must cost at least $6.
Two questions: Would the flexibility be worth it? And would this cause boards to be degenerate?