Forge
This card is way to complex…so I didn’t put a lot of effort in it and might not really work as intended
Will always be played regardless anything
When played:
- each and every combination of cards in hand will be considered for forging. The combination that results in the best card AND trashes the most crap (Curse, Copper, Estates, …) will be the one executed (best card = top card in buy rules that player wants at that moment)
Geronimoo's Dominion Simulator 
I’ve seen the simulator play a forge with 3 coppers and a curse in hand, but it was late game and the forge trashed nothing so that it could buy an estate. The first problem is that this breaks the rules as it should gain a copper when trashing no cards.
I’m guessing the card play needs to be changed so when the trashing is rejected to retain spending, the forge should then consider forging the non-income cards. If there is still nothing worth forging together then the forge isn’t played. The forge must still be played in some circumstances though (golem) and could then trash nothing to gain a zero cost card.
Forge doesn’t trash that hand because it looks in the buy rules for a card to gain and doesn’t find anything, so it trashes nothing. It should still gain a Copper according to the rules so that’s definitely a bug. I’ll need to revisit this code.