The key to this deck is, you guess it Spectral Pillager.  What I discovered about playing with this deck is the unnecessary number of cards that I see in other builds.  At it's core, this is a combo deck.  Which means, you don't need to prepare how to beat aggro decks... you're just going to lose most of the time.  There are things like Seal Fate, Eviscerate, Sap, and the like to deal with threats... but mostly you are going to be doing a lot of trading.

Another piece of advice is that your life total IS a resource.  Don't get caught up on your life total dropping low.  I have taken this deck down to 3 life and stared down the barrel at a lot of kill from my opponent next turn, then pulled off the combo to swipe the win away at the last minute. 

I don't worry about going face unless there isn't a board threat.  If your minions are the only ones on deck, swing away.  The key to getting this combo off successfully is to make sure that you have the at least one Umbral Skulker, Spectral Pillager, and Spirit of the Shark in hand when you drop Emperor Thaurissan.  You don't need it, but reducing the costs helps to ensure that you have enough mana to cast the cards you need to in order to drop a good amount of DPS.

I put in the quest for 5 reasons, the Licensed Adventurers give you that oh so lovely The Coin to help with combo, the Questing Explorers give you draw and a trade minion, Sky Gen'ral Kragg give you a taunt and a rush minion to help control the board.

If you pop Galakrond early, you are able to stock up on a couple of lackeys that will be great to gear up the combo, but don't get too caught up on that.  He is a means to an end.  You only need it to be invoked twice to get the Umbral Skulker's effect.  That is why there is so much draw in the deck.

With this build, I've been able to pretty much dog walk mid-range and control decks pretty easily.  Even Big and Highlander Priest is easy to take down.  Secret Mage and similar aggro decks are just hard.  Don't be discouraged though, just remember the formula:  Aggro > Combo > Control.  There are going to be exceptions to this formula, but it stands the test of time.  Have fun and let me know what you think of it after a like!

UPDATE~

I pulled the Elven Minstrels and one Spectral Pillager to make room for the Secret Passages and Sphere of Sapience.  Since you aren't really using your dagger hero power, and the sphere allows you to dive into your deck a little more, it is a great tool.  The minstrels were great, but having the 4 extra cards to play through and thin out your deck and potentially invoke Galakrond, the Nightmare a little quicker, why NOT use them.  I have also been toying around with Lorekeeper Polkelt.  It helps to ensure that you get the high cost cards in your hand when you want them instead of accidentally drawing them with a full hand, or to Mill decks.... which are the bane of combo decks.  Enjoy~!