Hearthpwn

EDIT 4/13 - Unfortunately, my guess is that the watchpost nerf destroyed this deck's viability and I don't recommend trying it anymore. It's a bummer, but I still think the skeleton of this deck is strong.

My Winrate over the past couple days is 77% (33-10) right now (updated 6pm EDT, 4/10). Proof:

I initially created this deck because I was tired of taking ranked seriously and just tried to combine my two most successful renditions of DH... but then I won 7 straight games, 4 of those against Paladin and Mage. After a couple of hours of near 50% win rate after that, I rocketed off with another long win streak... currently at 13 wins in a row that has carried me up to Diamond 4.

Based on how amazing Magehunter is in this strange meta right now, I'm blown away that more people aren't playing it. I've won a few of the above games simply because I was able to silence a divine shield taunt and kill them through it with our (better) version of King Krush. 

What do I do against Mage?

Your strategy against Mage should be to try to chip their health down as fast as possible and eventually end the game with a big swing from an Illidari Inquisitor and a weapon (and sometimes Fury). You can often kill someone from 13 health if you have a Marrowslicer equipped, and that's been my strategy against Mage so far. I'm sure this deck would lose to a super highroll Lunacy start from a mage, but I've been lucky enough to dodge those recently. It feels dumb to say kill them before they kill you or have a chance to heal, but that's literally our strategy. Don't forget, Illidari Inquisitor can attack their face even if it is frozen.

Okay, what about Paladin?

Paladin, the other deck that is everywhere, almost immediately dies if you:
1. PLAY AROUND THEIR SECRETS. This one is entirely on you, but a very important part of this matchup.
2. Use  a Magehunter to silence their Librams/buffs away. Doing this early can turn their deck into a strong, but very fair midrange deck that you can easily dismantle.
3. Star Student Stelina their particularly annoying card away. If they're holding something or are almost out of cards, get rid of that Liadrin/Libram of Hope and watch them hover over their hand in shock and sadness.

A few other tips:
1. Don't waste a Raging Felscreamer's cost reduction on a demon you create from a Netherwalker or Illidari Studies unless you really need the early tempo.
2. Feel free to remove Kargal Battlescar of Cycle of Hatred for either draw/early tempo/another big minion. This deck is not extremely refined yet, but I've never had a game where either of those cards have seemed to clog my hand and I've won the game because of both of them. The bonus to playing those cards is that no one plays around them because they aren't popular... and they're fun.
3. Don't get greedy with your cards. Kargal/Luckysoul Hoarder can bait you into holding on to them when it would be better to just play it on curve. 1 watchpost is often enough for Kargal to make an impact, and a Luckysoul Hoarder is hard for the opponent to remove and often just trades well into their minions.
4. If it isn't obvious to you, we want to win and hold the board for the whole game. Deciding when to stop trading and go face instead is something you learn over time and largely is dictated by what else you have in your hand.

Mulligan tips:

1. I highly recommend never keeping Fury or a big demon/card in your opening hand. Think of Fury as a burn card that you can draw later in the game. Before 5 mana, Fury is just a barely upgraded hero power and it's almost always better to just HP instead.
2. This deck has two "halves", with 7 cards in your deck at 7+ mana, and the rest all at or below 4. Because of this split, try to mulligan away anything that costs 4 or higher to find your cheaper cards. You should statistically start every game with at least a 3 drop in your hand opening hand and I've found that tends to be good enough right now.