Wow, I love this card and this time I approve the art and the name. So, this might be my favourite card from the set so far.
The main effect is sort of a Throne Room, but without playing the Action twice, it adds a cantrip effect to it. So, it's effect is probably not so strong, but at least it's never a dead card (unless you draw it dead of course). So, the power level might be similar. It combos nice with Apothecary, Cartographer and yeah even Scout. Chaining Heralds will be pretty crazy and King's Court + Herald even more because the order in resolving could get really confusing like kinging a Herald to reveal a Golem ... !?
So what are action cards that really want to be played as Cantrips. I guess most attacks, probably not cursers as the games are rarely engine boards, but playing trashing attacks like Knights as cantrips could be devastating. Other than that, Bridge comes to my mind. I wonder how good a Herald+Bridge game with trashing would be. Seems really strong. Also trashers are nice as most of them are terminal, although this gets probably dangerous with mandatory trashing. It has the same problem as Golem has, you really have to be careful with a Trading Post in your deck, for example.
The overpaying is basically on-buy Scavenger and seems also very strong. With top-decking like Royal Seal you could pair cards that you buy and from your discard. In every end game (especially Colony games) it might be really good to pay $5 or more to prepare your next turn just like Inn or Mandarin can do it.
Edit: Oh yeah, Wandering Minstrel comboes probably even better with it, but you draw first and then the next card has to be an Action card, that's a bummer.
Edit: 17 new replies have been posted. Sigh.