How it works:

This is a meme version of Mill Lock which is truly hard to pilot. It uses Octosari which is handed over to your opponent, in order to mill him to death. Survive the early game by controlling the board with removal spells and sticky minions/demons, until you assemble all the combo pieces. To go off, you must first have some of these pieces' cost reduced by Emperor Thaurissan. You have to draw as fast as you can, which means tapping your hero power several times. Don't be afraid to Mortal Coil your own Kobold Librarian, because the key here is to assemble all the combo pieces to go off. Time is of the essence and disruptive strategies like Dirty Rat, Deathlord and Skulking Geist, can ruin your chances to victory. Now, let's address some of the possible scenarios here:

• Make your opponent draw 16 cards for the fatigue OTK: You need Emperor Thaurissan, Drakkari Enchanter, Octosari, Baron Rivendare, 2 copies of Treachery, Power Overwhelming in hand. Double tick with Emperor and Drakkari (6+3=9 mana). Next turn play Baron and Treachery on him (2+1=3 mana) to pass him to the opponent. Play Octosari+Power Overwhelming (6+0=6 mana) to have it killed by the end of your turn. Pass it to your opponent with Treachery (1 mana).  Baron will trigger Octosari's Deathrattle twice when you pass your turn and for 3+6+1=10 mana you'll make the other player draw 16 cards for the OTK.

This combo is really hard to pull off, because it's consisted of 7 cards to be in hand at a given time. Moreover, it requires a "dead" turn since the Emperor+Drakkari combo costs 9 mana. This is possible after a Bloodreaver Gul'dan turn most of the times.

• Make your opponent draw 8 cards (easier to pull off): You need Emperor Thaurissan, Octosari, Treachery, Power Overwhelming in hand. Emperor ticks once and next turn you may play the other cards next turn for 7+2+0=9 mana.

PS:This means that you could probably miss up to one combo pieces (from Octosari, Treachery, Power Overwhelming) when Emperor ticks in your hand, without any consequences.

This might be the most viable strategy. Stall the game enough with the demon package/healing minions/removal and then go for milling a bunch of cards/fatiguing your opponent. This is why some other cards could be more of use here, like Coldlight Oracle, Brann Bronzebeard, Gnomeferatu, Deathlord etc, which might compliment but also change the nature of this deck completely.

• If your opponent plays Skulking Geist and destroys your Power Overwhelming, you can still pull off the combo (8 card milling). You will need Emperor Thaurissan, Drakkari Enchanter, Octosari, 2 copies of Treachery and Doomsayer. Double tick with Emperor+Drakkari (6+3=9 mana). Next turn play Octosari and Treachery on him (6+1=7 mana). Then play Doomsayer+Treachery (0+1=1 mana). Pass your turn and make the opponent draw 8 for 7+1=8 mana.

PS: The fact that this scenario actually costs 8 mana to go off, means that during the Emperor+Drakkari turn, you don't need to have in hand up to one of the other combo pieces (from Octosari, Doomsayer or one copy of Treachery).

• If your opponent plays Dirty Rat or his Deathlord dies, to bring Octosari on the board, then you are most probably in luck. During your turn you can just use Power Overwhelming+Treachery on it (1+3=4 mana), or Treachery on it and the Doomsayer+Treachery combo (3+2+3=8 mana) and pass your turn. I guess there can be multiple scenarios like this one, so keep your eyes open for any opportunity that presents itself.

Things to keep in mind:

• The opponent must have 2 open spaces for your Octosari+Baron or Octosari+Doomasayer and you should have at least one, when the combo goes off.
• To calculate fatigue-damage fast, use this formula: (n/2)*(n+1), where n is the number of cards drawn after his deck is depleted. Since the fatigue damage from the combo is dealt to your opponent during your turn, remember that he will draw again during his draw phase and get fatigue damage once more.

Replacements:

Replaceable cards are Lord Godfrey, one copy of Hellfire, Antique Healbot, Mistress of Mixtures. You can add another copy of these ones or add one copy of Twisting Nether, Sacrificial Pact, Siphon Soul, Power Overwhelming (for consistency/clearing a healthy minion). Don't add any other demons, because it will ruin your Voidcaller/Voidlord combo.

If you don't have Baron Rivendare, drop Drakkari Enchanter and Mistress of Mixtures as well and put 2 copies of Coldlight Oracle or Gnomeferatu and Brann Bronzebeard to your deck for double milling or healing with Antique Healbot. This version of the deck feels more viable to me and I would definitely recommend it.

Mulligan:

Aggro: Kobold Librarian, Mortal Coil, Mistress of Mixtures, Doomsayer, Voidcaller, Defile, Hellfire.

Control: Kobold Librarian, Voidcaller, Sense Demons, Emperor Thaurissan.