I created 3 cards based around a theme of manipulating supply piles, incentivizing more careful consideration of three-pile-endings. While certainly not the preferred type of game for many, I wanted to present these non-playtested sample cards to see how others thought about supply pile manipulation as a mechanic. I tried to be careful regarding swingyness, making such mechanics too 'front-and-center' in any kingdom, and balance regarding turn order and player count - but these cards haven't been tested and are more a
thought experiment. Let me know if you think any form of these could have any value:
BURNBurn (part of a split pile) allows trashing from action supply piles. This might empower certain play/gain from trash cards like Rogue, Lurker, Necromancer. Most significantly though, Burn can be used to leverage three-pile-endings, though the "once per turn" limitation, and the fact there are only 5 cards you can buy to activate the when-gained effect, helps prevent the card from being too swingy. The ability to run down certain piles creates certain tactical considerations - like whether you have enough time to build up your deck before getting X cards. It might create a runaway leader effect however, and if spammed can empty 2 whole other piles rapidly - this might make a pile out too much of a looming threat and disincentivize any sort of building. Though to spam it, one would need to have gotten +Buys and some VP points to feel safe doing so.
SWIDDENSwidden, the card below Burn, offers itself as a weak sort of peddler that might, in the later game, enable some moments of strong buying power. At a cost of two, and its effect being optional, this cantrip's pile could be run down quick. However, it can offer some mild defense against pile-outs - and once all Burns have been gained, that defense might be enough to really matter.
DAMLastly, Dam - the idea here is that you can take any card and put it on a non-victory pile (for example, take your Smithy and put it on top of the Laboratory pile, forcing that Smithy to be bought as its normal price before one can buy the Labs below it). It offers (1) a defense against pile-outs, (2) a small source of VP to safeguard against a quick ending, and (3) a sort of attack that would make it harder for players to gain the card they want. As a sort of trasher you can cover piles with your loose coppers, curses, and estates, requiring the other player to lose a Buy to get to the card they want. Laying down more expensive cards from your hand offers an even stronger road block. To ensure the card is not ruinous in a kingdom without any +Buys, Dam comes with +Buy itself. It also is a terminal with no other significant effect. The targeted pile needing to cost 3 coin or more has two justifications: a fear of its interaction with the Swidden/Burn pile, and the idea that a pile costing only 1-2 should be easily gainable.