Hunter's Mark is a pretty efficient tool to get rid of big threats. You'll generally combo it with Wild Pyromancer to provide a Swipe effect at the same time or with Steamwheedle Sniper for a lonely target. 
Note that Acolyte of Pain and Boom Bot are also pretty good at trading into your target if you have the opportunity to do so.

Arcane Shot is generally used to get rid of early threats. Using it in conjuction with Wild Pyromancer can create some really efficient board wipes to deal with swarmy Decks.
Don't forget that the damage can also trigger Gahz'rilla effect or go to the face for the finishing blow ;)

Wild Pyromancer is here to apply the damage you lack onto the opponent's board while triggering Acolyte of Pain. 
Use it with the previously mentionned spells or some traps to get finish off your targets and don't hesitate to suicide it by triggering the effect twice if necessary !

Steamwheedle Sniper is an awesome addition that can make the Deck viable once again as your hero power now becomes a Control tool with it. 
It will help you finding the damage you need without wasting too much resources, either being on a Snipe or Hunter's Mark target, a simple Knife Juggler or in conjuction with Eaglehorn Bow to deal with a Sludge Belcher.
After realizing that I generally only need one, I decided to swap one of those for Big Game Hunter as it is just too valuable in the current meta.

Feign Death is another very good tool brought by GvG. I have to say that this card is insanely strong and can lead you to build some pretty strong boards !
Obviously, combining it with Sylvanas Windrunner on turn 8 is its primary use, especially if you can have some other Deathrattle minions on the board for maximul level of value but don't forget the limit of 7 minions xD
I also found it quite useful with Boom Bot from Dr. Boom and you can also use it with 2 or 3 of your most valuable Deathrattle minions to increase your board advantage ;)

Mad Scientist is really great to have some early presence and pull out traps from your Decks to keep up on card advantage and sustain your Eaglehorn Bow. 
As the Deck is applying constant damage, you are generally ok with whatever trap it will give you so that's a good thing and don't forget that you can play a trap from your hand to make sure it pulls off the other ;)

Explosive Trap is mandatory to get rid of aggressive Decks and the damage to the face is also always good to have.
Snipe is really good in this new meta since it kills plenty of Mechs and beefier targets can be finished off with your other tools, pulling this for free can give you huge tempo advantage.

Eaglehorn Bow complements this trap engine to control the board efficiently or apply some more damage to the opponent's face later on.
It's especially great to deal with semi-aggressive Deck as you can kill off some pretty good targets with it like Mechwarper.

Piloted Shredder and Sludge Belcher are replacing Sen'jin Shieldmasta and Azure Drake from my old build to provide some mid game value minions and adjust the curve.
Piloted Shredder 4 attack can help you controlling the opponent's board and its Deathrattle effect has not to be underestimated and the sticky Sludge Belcher will help you tempoing the opponent for you late game plays.

Loatheb is still a really strong tool to use after the new expansion as it prevents board wipes, can set up lethal or stop your opponent from finding it. 
It's both good to increase your momentum or coming back from slightly behind ;)
I finally decided to craft Harrison Jones so swapped them as it is just too valuable in the current meta.

Savannah Highmane is obviously still in the Deck for its aggressive stats and awesome stickiness.
This Lion King is basically my favorite card in the game and is basically the reason why I love so much Hunter !

Sylvanas Windrunner makes an appearance in the Deck for its obvious synergy with Feign Death which can be completely game changing.
The card is already good on its own so it's a perfect addition to the Deck.

Dr. Boom hell yeah ! I love this card so much and I have to say that it has been an MVP for me when playing this Deck. I wasn't so conviced at first glance but decided to give him a shot as I opponened him in packs and it is pretty amazing as it can be very useful from slightly behind or when ahead.
Those Boom Bot are pretty annoying for your opponent and can really help you controlling the board or finding damage onto the opponent's life. The fact that you can trigger them with Feign Death before using them is just the icing on the cake.
The fact that it is a Big Game Hunter target is almost a good thing since you want to protect Ragnaros the Firelord from it.

Gahz'rilla is a really nice addition to the build as it will induce so much fear from your opponent, forcing them to waste ressources to get rid of it.
Obviously, if they don't deal with it it's pretty much win since you have many ways of triggering its effect : Arcane Shot, Steamwheedle Sniper and Wild Pyromancer for maximum level of value !

Ragnaros the Firelord is still in the Deck as your final win condition because synergizes pretty well with the Hunter game plan. 
You'll generally play him for the win in a situation where it either kills off a big target or goes to the opponent face for lethal or at least a nice chunk of damage which will lead you towards that.

Freezing Trap doesn't really fits the Deck since you can't control efficiently which target will be returned and killing tragets is preferable than returning them to your opponent's hand in the current meta.
The set of traps that I'm running works way better with all your small damage tools since you can finish targets easily but it's still a good card to consider if you adjusted the build differently or depending on the metagame ;)

Explosive Sheep is a very interesting card to use with Feign Death or even Wild Pyromancer. 
After testing it a little bit, I ended up cutting it off because of its very situational nature but it's still something to keep in mind for the future depending on how the meta evolves.

Illuminator was another card that made me thought about bringing back Hunter Control. 
I initially runned both copies and after testing it I found them a bit underwhelming so I chose to run only one. It was decent honestly but not as good as the second Wild Pyromancer / Snipe / Arcane Shot.

Baron Geddon from my old build can still be used in the Deck but after playtesting I'm favoring Dr. Boom. 
It's still a perfect replacement for this card if you don't own him though ;)

Sneed's Old Shredder seems like a perfect card for the Deck as it can give another value to Feign Death. However I didn't obtained in packs and I want to wait before crafting cards to test them.
I'm not sure how I would fit him in the Deck but I guess you could try instead of Gahz'rilla, even though I like the card I feel like running too much win conditions is kinda greedy and not necessary.
Let me know in the comments how this card is doing in the Deck if you try it ;)

Harrison Jones seems like a very good choice over Loatheb in the current meta. I ended up crafting him as it fits the slot perfectly !

Big Game Hunter is a good card to consider in the current meta as there are many Handlocks and Warriors around.
He is currently in the Decklist because basically every Deck is playing Dr. Boom so you'll have a target for it very often.

The Black Knight is another obvious tech card that you may want to include depending on how the meta evolves.

Here are the priorities if you are planning on crafting some : 
1. Ragnaros the Firelord : Your most favorite bomb, will be useful in any other Control Deck.
2. Dr. Boom : I already explained in the write up how well it worked out for me and it is a pretty good card to have for Warrior Control also.
3. Sylvanas Windrunner + Feign Death : You pretty much need the second one to justify the other since the combo is so powerful, those are also good cards in general.
4. Gahz'rilla : The least important one to have but still very good in this Deck.

If you are not planning on crafting those, I suggest you to take a look at the Consideration section where some tech cards are listed. You may want to include some of them depending on the state of the metagame ;)

Here are some good cards that could complete the set of late game threats if you are lacking some but are less optimal overall :
Legendaries : Sneed's Old Shredder, Kel'Thuzad, Baron Geddon, King Krush, Deathwing, Troggzor the Earthinator, Cairne Bloodhoof, Loatheb
Epics : Faceless Manipulator, Piloted Sky Golem, Gladiator's Longbow

You can try out any other win condition that you may have and like but remember that a Control Deck relies on its win conditions to be very consitent so it will still be sub-optimal and will certainly hurt your success with Deck unfortunately =/