Hinterlands 2E! What were the odds. But here it is.
Each day for 3 days I'll show 3 cards leaving, and the 3 replacing them, and talk about all six. The last day will throw in the miscellaneous minor errata, and then more minor errata, for other sets. Oops that errata's been spoiled already somehow. Well it will happen then.
As with the other two sets, I had no specific objective for Hinterlands beyond... actually, you know what? This set could use more of a theme. I love having lots of when-gain cards, but it's just a bit invisible. What about... Reactions? The set already has three of them. Yeah, let's go with that. A Reactions subtheme. And then, just taking out bad-to-print cards for good-to-print ones.

Mandarin is very weak. You heard it here. Good rules of thumb: never get involved in a land war in Asia; don't buy Mandarin.
Weaver has no relation to it; Mandarin was doing nothing for the set. Weaver is a Reaction, starting in on that new subtheme. It's a Workshop, and you can play it when you discard it. Also fitting Hinterlands' other invisible theme, which is filtering.

Embassy is dull but okay; it lost out on numbers. It was a borderline card that people really didn't need to exist.
Wheelwright is unrelated. You discard a thing to gain a thing. Another way to discard those Tunnels and Weavers. And note that it's the second new way to gain cards, for the set where cards do things when you gain them.

Oracle isn't weak or strong really, but it's crazy slow. It's the bane of playtesting; they endlessly flip over the card you actually wanted to playtest. I haven't played with it in years, except for one game to make sure I really wanted to get rid of it. I did.
Witch's Hut again ties into the filtering theme. It's both the new Embassy and the attack that replaces Oracle.
As usual, the preview cards will be playable on dominion.games; in fact for those of you who aren't subscribing, previews will include all of Hinterlands.