The idea behind this deck is pretty straightfoward: You have your main win condition - Using Treachery into your Unlicensed Apothecary, summoning Leeroy Jenkins and then dealing a blasting amount of 16 damage right into your opponent's face!
Now, if your opponent's deck is just either way too fast or has too much heal/armor, you can save up Treachery to use into your Howlfiend and packing it up with Defile to straight up delete his card advantage, if any.
The deck is pretty much aggro-proofed, having lots of taunts (such as Tar Creeper and Voidlord, also featuring the standard Control Warlock removals and its ability to clear the board with ease.. Perhaps even in a better way). In my experience the only kind of archetype this deck is relatively weak to is Heavy Control, such as Control Mage and Cubelock.
However, by no means it's an easy task to play with this deck, since there's lots of macro management involved on it... So, good luck!
If you have any suggestions, just write it down here.