Hearthpwn

This is a boss that opens with six mana worth of free Troggs on the board, and his hero power interferes with your ability to play your cards.  You can't cast spells on even-numbered turns, and you can't summon minions on odd-numbered turns. 

Hunters have a bunch of early game removal, so they excel at killing PvE bosses whose difficulty is built around them opening with free minions.  Your ideal opening hand is a Hunter's Mark and a Misdirection, so you can crash his two Troggs into each other.  Once you have that, start clearing the board and recovering; from here on, he's just like normal-mode.

Since this deck is spell-heavy, try to set up Lock and Load combos to offset the card advantage he has.  A turn 6 Savannah Highmane should lock the game up.  

If he plays a secret, it's the new Dart Trap, which deals 5 damage to a random target when you use your hero power.  So, don't use your hero power if he has a secret.