Here's a real silly/broken one.
BEAN FARMER
$6
Action-Attack-Duration
When you play this card, every player (including yourself) shuffles their hand, places it on their deck, and draws five cards making sure not to rearrange them, with the top card on the left. Until the beginning of your next turn, every player must play their cards in order from left to right (with all drawn cards added to the right end of their hand). Any single-type Victory or Curse cards, as well as Action cards which would be played after the first Treasure, are instead discarded. At the beginning of your next turn, discard Bean Farmer.
And an homage to Chicago Express and its (excellent!) dilution mechanic:
STOCK CERTIFICATES
$6
Victory
At the end of the game, add the number of Stock Certificates in the initial Supply (either 8 or 12) to the number of Provinces in all players' decks. Each Stock Certificate is worth that number of VPs divided by the number of Stock Certificates in all players' decks at the end of the game.
That's just got to be way too strong, but whatever, it's late.