Overview

So I didn't make this deck up, it's from HSReplay, but I have played a few hundred games with it.  There are a lot of mech hunter flavors out there.  This deck I consider the most all-in version, as it doesn't have contingency and tech stuff and just goes for the standard mech value strategy.

This is a value-oriented mid-range hunter with an 8 mana combo (Venomizer + Missile Launcher) for a clear/pressure WC and an alternative win condition based on forcing a clear into bombs.

Mulligan

This depends largely on if you have the coin and what the opponent is.  There is no 'general' strategy.  Depending on your opponent, you probably want to get Fireworks Tech and Mecharoo.  This is a strong launch combo that establishes on 2, throw it down all at once so they can't kill the Mecharoo. The other tactic is to try for Ursatron and Galvanizer to pull and discount the combo while establishing a semblance of tempo.  Bomb Toss is almost always a keep against aggro.

So let us consider the deck to operate in two forms - vs control/mid and vs aggro/zoo.  The deck can operate against either opponent, but the play is quite different.

Proper use of Tracking

• Deck Thining:  Use this to remove cards you don't want to draw later- can also get rid of bombs.
• Against Aggro:    This card should be kept and used immediately to fish for early tempo like Fireworks Tech or Mecharoo.
• Against Control:  This card is for deck thinning and assembly of the Venomizer + Missile Launcher combo.

Proper use of Galvanizer

• Against Aggro:   Use it earlier to out-tempo them and hold the board. This will deny a launch platform for things like murloc buffing or mech slamming.
• Against Control:  Hold these as long as possible to get the biggest discount on the combo pieces and support mechs.

Matchups

• Shaman: There are two flavors of shaman out there - murloc, and aggro overload.  The strategy is the same against both - early tempo using Mecharoo, Fireworks Tech, and Replicating Menace to keep them at bay until your bigger threats show up to overrun their limited production.  Focus on killing these minions - Thunderhead,  Spirit of the Frog, and Underbelly Angler to spoil their win condition.  This one is a toss-up.  If they get ahead, you are finished.   Usually comes down to draw.
  
  
• Druid: This is your nemesis.  They will try to out-tempo you and build a board early.  They will be much better at it than you.  The choice is how much to push tempo vs trying to pull the combo.  If you can combo after they buff but before they attack, you can win.  Of course, Soul of the Forest is a thing that sucks too.
  
  
• Mage: You see a number of these.  Most are of the 'big' minion variety.  They will have freeze and clear, giants, minion duplication.  General strategy is to try to split between early aggression and the combo.  Mage won't put out tempo early-game so you can try to keep ahead and when they slap down the huge board, you combo.  Mage feels like the underdog against this.
  
  
• Priest: This class has a low profile in the meta.  Most are silence so the game plan is like mage, but easier since their early tempo is weak.  Problem is they have tools to deal with your combo so you may need two of them or leverage Spider Bomb somehow.  If they are trying to draw, it is Nomi Priest, rush them down as fast as possible and save a combo for when they Nomi, should be a fairly straightforward victory.

• Warlock:  Let me know if you see one.  But seriously, give the state of warlock right now, just wing it.
  
  
• Hunter: This is going to be either a mirror or a secret-mid type.  There are a few beast hunters out there who try to draw fast, but not common.  The play is more aggro, but you need to eventually get the combo to wipe their board, especially in the mirror.
  
  
• Paladin
• Rogue
• Warrior: One of the reasons I like this deck is that it doesn't struggle against warrior as much as murloc shaman or aggro shaman.  First off, you will need the combo.  They have armor, removal, and can pump out in the late game.  Early tempo doesn't really matter in this one.  Focus on Bomb Toss and Galvanizer while you hunt for the combo.

Other Cards

• Necromechanic
  • This card seems like a fit since it can be comboed with [Hearthstone Card (Boomaster Flark) Not Found] but it's awkward, and you usually just get run down in a tempo race if you try the combo. Not advised to include.
    
    
• Mechanical Whelp
  • Not magnetic so its kind of heavy, but it can win games when you pop it in various ways.  Obviously, Fireworks Tech becomes a lot more crucial in the mulligan and draw.  A reasonable include
    
    
• Leeroy Jenkins
  
  • Now included in the deck.  Good burst finisher, or earlier to get them into the death zone.  Combos with Missile Launcher to kill the whelps and helps in the endgame for pressure or when you don't have a mech to go face with.
    
    
• Mossy Horror
  • Another option that can be comboed with [Hearthstone Card (Boomaster Flark) Not Found] but it's only 8 damage and the Mossy Horror has no other use because by the time you can play it, they will have a board buffed to the moon, especially murloc and druid.  Not a wise choice.
    
    
• Safeguard
  • Really more of a 'lose-more' card for mech hunter.  There are stronger strategies for dealing with aggressive builds.  A weak include.
    
    
• Whirliglider
  • I like this card, especially against aggro, but the deck is stuffed already and [Hearthstone Card (Upgradable Framebot) Not Found] is just better because of the survivability afforded by 5 HP.  Mech decks need to focus on magnetizing and slamming every turn.  People facing mech decks need to focus on eliminating all opponent mechs every turn.  Since framebot is a common, there is no reason to even consider Whirliglider.
    
    
• Skaterbot
  • A good card if you are struggling against big boosted minions when facing control.  Gives you a way to pop your dethrattle and generate some tempo.  Include as you deem needed based on meta.
    
    
• King Krush
  • So I love this card, but I just can't keep it.  It does win games, it does feel amazing when they think they have another turn and then the stomping sounds and boom before they can click concede.  But overall it is just an albatross in a deck that can not afford a loss of early tempo.  Find your own path on this one, it is a blast to run.
    
    
• Marked Shot
  • This one is strong, but the four slot is already populated with crucial minions that are required to establish the launching platform for the closing turns.  It also runs against the aggressive doctrine of using superior minion pressure to force them to trade or take damage.  Still, a spell discover can be pivotal, so it really is up to the player's preference if the benefit of removal/discover is worth delaying the launch of the endgame for a turn.
    
    
• Nine Lives
  • I like this card, it is a strong tempo play that gives you a draw.  Problem is that magnetic is awkward so if you hook a Spider Bomb to a mech on the board, it won't be discovered by Nine Lives.  I played this card in the original deck recipe (Scrap Heap), and loved it, but there is no room for an underperforming card.
    
    
• Dire Wolf Alpha
  • A solid include for this deck - provides early game tempo and a means to pop bombs in the late game.