Strong deck if you draw N'Zoth, the Corruptor or Coldlight Oracle early enough. In most of the times you should play N'Zoth, the Corruptor before playing Coldlight Oracle and Vanish. It's almost an insta-win if your opponent doesnt kill N'Zoth, the Corruptor behind all your taunt minions, and all you do is, play him again and again.
Important: Never gang up N'zoth more than 1 time, it's enough! It's better to use the other gang up for you coldlight oracles or healbots (healbots only if needed)
Why Doomsayer in Mill Rogue?
Doomsayer is a great card to stall. Good Combo: Vanish + Doomsayer to get an extra turn most of the time. (This combo is even better if his hand is already full and your opponent has to play something)
I even made it to Legend with this deck (just rank 1 to Legend, the other part was my oil list)