Early game, keleseth of course, man ari only with the coin.
Despiciable Dreadlord only against odd Paladin, early game you know keleseth bla bla bla, and shadowflame because it's a clean. MCT can be good but not every time, depends of your hand.
Keep skull with coin, you might have the time to play it against midrange, and early game.
Current controles like hunters, droods, warriors have many 1 cost spells so Geist is beast. Gul'dan can be also a win condition, keep it if you have the coin. Skull is a great way to kill controles quickly, they can't remove everything. And early game is important too but not void walker sometimes to weak (depends of your hand)
Let me present you my Midrange- Demon Warlock whith whom I destroyed the top 1000, from 950 to top 90 (65% win rate)
The “start potential” of the deck can be insane (Prince Keleseth,Skull of the Man'ari ) , it’s a really stable deck in general with our early game, and a bad hand can be quickly changed into a good one with the Skull of the Man'ari, not that much Gluttonous Ooze in the current meta. The strenth of the deck is that with Skull of the Man'ari you can summon good demons each turn for the rest of the game. But we perfectly can win games without the weapon. Skulking Geist is absolutly beast in the meta, destroying Soul Infusion can even be nice for us in late game.
What about match ups:
-positive ones: Hunter, Druid, Zoo, odd Paladin, quest rogue
-50% win rate in general against: odd rogue, controle warlocks, shamans, odd war
-bad ones: , tempo mage.