Here's my take on a really early theorycraft for a post-rotation mage deck.

The plan is to survive the early game using cheap spells like Arcane Explosion, Cinderstorm or Frostbolt plus Bloodmage Thalnos and your heropower, buffed by Daring Fire-Eater. For zoo or aggro you can also go for the usual Frost Nova + Doomsayer combo, Cone of Cold further helps stalling.

Hopefully, we have Jan'alai, the Dragonhawk ready by turn 7, our first big threat and bait for hard removal. By turn 9, it's time to get out the big boys: put out Alexstrasza, Malygos and our new value machine, Kalecgos. Between those three, Jan'alai and our spells, our opponent should quickly run out of answers.

Looking at all those survival-tools, draw might become an issue. That was the reason to run Pyromaniac and two Arcane Intellects. In slow matches we can even turn this into value and get out a big Astromancer.

I'm hoping for more new and interesting cards from shadows to add and would appreciate any feedback. Thanks!