Inflation, Event costing .
Take an extra turn after this one in which cards cost more (but not more than infinity.)
That's some combo potential with Livery!
You all are massively underselling the combo potential. With Salt the Earth if you can get your deck to just Treasures and a Sanctuary (with enough Gold and Silver to hit $9) you can buy Inflation every turn (you will always hit $5 with only Treasure and the Sanctuary being an cantrip), endlessly, and when you play the Sanctuary and hit $9 you can buy both Inflation and StE. If there are no empty Supply piles when you start, you can trash every card from three VP piles, plus all but one from the rest, easily netting you 20+ VP (and in games with Colonies and one Alt-VP, easily 30) and ending the game without your opponents ever getting to take a turn.
Similarly, with Delve if you can get your deck down to just a Salvager, 1-3 Coppers, and at least 1 Silver, you would again always be able to hit the $5 to buy Inflation. After buying it 30+ times (or possibly more in games with additional Silvers on the pile), the next time Salvager collides with one of your Coppers you use the Salvager to get $60+ VP, then use Delve to pile Silvers. After that buy a Feodum every turn (they will be worth 10VP+).