So far the fastest way I can find to pull this trick is a turn 5 win on rogue.
Turn 2 Preparation into Myra's Unstable Element
Turn 3 Hallucination or Blink Fox getting Cataclysm.
Turn 5 Myra Rotspring gaining Mecha'thun's deathrattle, coin, Preparation and then Cataclysm.
inb4 you are matching up with Warlock. This is definitely some Trolden material.
3
Pretty cool.