Hearthpwn

First, let me say that Mage is probably better suited to this boss fight, with freezing spells and minions that can keep Netherspite from using its hero power. That said, I wanted to make a Hunter deck (I plan to make a Mage one at a later date).

Strategy: Keep a minion blocking the pink portal to prevent Netherspite from using Windfury. Keep a taunt minion blocking the blue portal; this serves two purposes. First, the minion blocking the blue portal can only take one damage at a time, which makes your taunts last longer. Second, blocking the blue portal is essential; if not, Netherspite becomes immune to your attacks.

Play your taunt minions only on the blue portal. Never play them on the pink portal.  Wait for Netherspite to smash one taunt down before laying down another. If you are in a jam and need to block the pink portal and only have taunt minions, go ahead and put a taunt on the pink side if it is all you have, but it will be destroyed in one turn. 

Play your charge minions like Argent Horserider, Bluegill Warrior, Leeroy Jenkins and King Krush along with support minions like Glacial Shard, Friendly Bartender, Antique Healbot, and anything else that isn't a taunt) on the pink portal side that has Windfury. The only exception to this is Nat Pagle. Always play him on the blue portal side, after you have laid down a taunt. 

I have found that by not putting down more than three minions on the board at once, Netherspite seems to use his spells less frequently. But he still uses plenty of spells! He has two Twisting Nether, Starfall, Starfire, Swipe, and other spells to remove your minions from the board or reduce their health to 1, just to name a few. 

When you have leftover mana, use your hero power to whittle down Netherspite's health.

Always keep a taunt minion on the blue portal to prevent Netherspite from smashing your face.

The best opening hand would contain Glacial Shard (use this immediately on Netherspite's face to prevent his incoming Windfury attack; play it on pink side) and any one-cost or two-cost taunt minion. If you get Nat Pagle, keep him but wait until you have a taunt to play him. Your taunts will keep you alive in this match-up.

Nat Pagle provides important card draw for tempo. Arcane Nullifier X-21 is a great taunt because Netherspite does not seem to be use his hero power against it.

Your minion directly next to the pink portal has Windfury. Put your strongest attack minion there (not your taunts, though -- save those for the blue portal). When it is your turn, first attack with whatever is in the Windfury position that is already on the board. Then add your strongest support minion to that spot (with highest attack) so the Windfury will do more damage next turn. 

This is an easy battle, but there is some RNG involved, so you may occasionally get a bad match-up. 

So for those who enjoy Hunter, this deck is for you! 

Enjoy!