Mill druid, basically gain a bunch of armor with ferocious howl and fatigue your opponent to death with naturalize. I managed to fatigue an opponent with call to arms/knife juggler to death on turn 7.
Edit: Changed Ferocious Howl for Branching Paths.
Testing now with branching paths, basically the same strategy but branching paths is slightly more flexible. Either way, this deck is auto win to a lot of aggro decks. Downside is that it loses to one of the most popular decks, mana wyrm missiles.
Currently 9-5 with the branching path version of the deck. 4 losses were to mana wyrm decks and 1 loss was to molten blade spellstone warrior who got twig of world tree :P. Other than mana wyrm decks it was pretty easy. You can easily outlast burn decks and any minion based decks just get fatigued. The only exceptions are mana wyrm + burn such as missiles or frostbolt because those decks have poor refill but loads of damage and naturalize gives them refill.
Against druids: Mulligan for branching paths
VS Twig, Starfire druid: when possible, just gain armor with branching paths. If you're on the coin, coin out branching paths for 12 armor and use branching paths again for 12 armor on turn 4. This should keep you out of range of the initial burst of starfire druid. After that, just gain armor with branching paths. Unless your draw is absolutely garbage where your hand is full of naturalizes, it should be easy. 15 starfires is only 75 damage, therefore 7 branching paths is enough to heal you out of their max damage range. They draw too many cards and fatigue themselves to death.
VS Other mill druids: If they use ferocious howl, then they just kill themselves from draw. If they are the same deck as this, it's a matter of who drew more branching paths. If they use forest guild + naturalize, you cannot win unfortunately. However, that version is very unpopular so it's not a big problem.
Against Priests: Mulligan for branching paths
If they're mindblast priest, just out heal them using branching paths. Similar to that of playing twig druid. If they are any priest deck that runs minions, it should be easy game. *Be careful of decks that run radiant elemental. Maybe they're radiant + mind blast, in which case you just out armor them. Don't naturalize radiant elementals, just gain armor.
Against mages: Basically unwinnable sorry :P Concede maybe?
Against shamans: Easy matchup, just naturalize all their minions and they die...
Against paladins: Easy matchup, just naturalize all their minions and gain armor with branching paths. The only exception is murloc + rebuke. That's just unwinnable sorry :P. Any deck that runs call to arms just loses to fatigue on turns 7-8 so it's really easy as long as you live for long enough. Make sure you use gain armor/draw a card very effectively. Sometimes drawing for a naturalize can heal you for more than 6 and it's just worth it to get them closer to fatigue.
Against hunters: If they run minions, just naturalize it. If they don't, just out armor them.
Against warriors: If they are upgrade + weapon warrior, you cannot win because they have too much damage. If they are weapon + spellstone warrior, just naturalize all of the golems and gain sufficient armor to survive their weapon damage. Make sure you don't let their golems attack. Drawing for a naturalize to kill their golem is more valuable than gaining 6 armor and leaving their golem up.
Against rogues/warlocks: Non existent classes lul. I don't know what decks exist for these classes so I guess you just fatigue them?