I think this is as good as it will get for Singleton Hunter. I know that brann doesn't seem like a powerful minion, but he's basically janalai, and he's a lot better than you think he is. Also, zephrys is an insanely powerful card if used correctly. I do think that is worth the build around. The idea with singleton decks is to create a deck that is as versatile as possible. You're a jack of all trades. Building a singleton deck is not actually that big of a downside. I played this deck without all the new cards a few times today and surprisingly won several games despite having a completely gimped deck. I would even argue it is a plus. Having an excuse to create an extremely versatile deck is technically an upside. Anyway, here's the list, and further explanation in spoilers.
Hunting Mastiff this card is bad. but really good in this deck, because it gives you the option on turn 4 (which is lacking) to either play 2 2/1s or deal either 4 damage or 2 damage twice, and also allows you to deal 2 damage on turn 2 or play a 2/1 on turn 2. it provides you several different functions. that is exactly what this deck needs. I consider this a staple in the deck. Back in the day, renolock used to run that 2 mana lifesteal deal 2 damage to a minion card. Hunting mastiff is better than that card.
The mech package Snip snap's a GOOD (not great) play on turn 3, turn 6, and turn 9. Ziliax is an auto-include in this deck even if it had no mechs. It's too good. The inclusion of ursatron allows you to put a replicating menace into your deck, which does three different things - 1. it justifies using ursatron. 2. you now have 3 mechs with magnetic in your deck and a card to tutor them out, which also happens to be a mech. 3. you have another turn 4 play (which this deck is lacking)
The big spell package Baited arrow, explosive shot, and unleash the beast combined give you a reason to run sunreaver warmage. sunreaver warmage is a really good card.
Vulpera scoundrel this card is going to be in many decks. It has an empowered discover effect, something we've never seen before. you are almost guaranteed to get a very good card with this. because of the fact that you can pretty much pick and choose what you want, this card's flexibility makes it an auto include in the deck. I am surprised this is not a legendary minion.
Siamat this card is going to be in almost all minion based decks. it is a (way better) neutral fireland's portal. it is one of the most flexible minions in the entire game and it comes at no downside. all options are good, but in particular, divine shield and rush are going to be the most popular keyword combination.