Mulligans
General Mulligans
The best way to win with freeze mage is by getting a large amount of card draws which allow you to respond to the board and set you up for the combo. Against aggro decks (e.g. zoo) I recommend keeping a doomsayer as it can kill their early game and reduces damage. Against control decks you can afford to play more slowly and focus on finding Alexstrasza or Malygos.
This is a different version of freeze mage that has both Alexstrasza and Malygos as win conditions. Using a combination of Malygos and emperor thaurissan it is possible to deal 32 damage in one turn. Or simply kill the the opponent with the classic freeze mage strategy of Alexstrasza followed by next turn lethal.
I enjoyed experimenting with this deck and had a decent win rate.