decrease port quantity 10% + x where x is equal to the volume of extra turns invested in this card divided by 1/2

Suggest a New Curse?

.. yes

Good idea, but whats it's rarity? Uncommon? How many turns does it cost? All essential information for good feedback.

Rare is nice, at very least uncommon. With ability like that stacks of Ruined Harvest can change the economy more than Fertile Lands do. Or maybe limit the usage (I.e. one per market restock)?

P.S. FYI card suggestions have their own forum