Hearthpwn

Reached Legend with this deck after a week of playing some games while I otherwise had downtime.

Performs very well against aggro provided you dont suffer horrible draw, with an overall winrate of roughly 75%.

Mullgian should be for low cost spells that eliminates aggro decks' ability to swarm the board and put your health pool to dangerous levels before you can completely control the state of the match. Examples are Arcane Missiles, Arcane Explosion and Cone of Cold. As I am sure is no suprise, your objective is quintessentially to limit their ability to spin out of control by exhausting their early resources. During the midgame is when you essentially win most of these games, where major board clear such as Flamestrike, Blizzard and Baron Geddon lets you dominate the board. Polymorph should be reserved for Doomguard, Gurubashi Berserker and similar cards that are difficult to get rid off effectively with the other kit you have available. 

Worst matchup is most certainly handlock, which beats this deck every time in my experience. Luckily I did not encounter too many in ladder, as its saturated with "people" spamming zoo variations. Ramp druid also gave me some troubles every now and then, and the matchup is essentially a toss up. 

This deck performs suprsingly well against control warrior, but comes down to fatigue every time. During the early game your only focus should be on limiting their ability to generate armor. Armorsmiths are your worst enemy. Save bigger freeze spells for Grom and other dangerous lategame finishers. Your winconditions are attrition by fatigue and Faceless+Polymorph their Ragnaros, Grom etc. after they have exhausted their arsenal of removal. Your Alexstrasza should be used defensively during the very-lategame.

As for its role in the meta, I personally find that this deck outperforms control warrior while also being cheaper significantly cheaper to craft, both of which was the intention when this deck was designed. 

Besides this the deck finds success against most other archetypes. Best of luck to you and thanks for checking the deck out! :)