Observer looks nutty. 4 health is awkward to deal with and potential payoff is huge. It's easy to imagine it running away with a game.
Stablehand I have reservations about. It reminds me of EVIL Recruiter in terms of set up and payoff. That card wasn't very good.
Tremors seems good to me. The worms die easy, but they must be killed or they'll trade up like crazy or do a lot of face damage. It's an annoying card. It's like barrel. Individually they're cheap but they can muck up the opponent's turns a lot.
I don't think any of these cards really fit in hound hunter unless the deck wants a more aggressive slant.
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