There are a couple different ways for you to finish off your opponent with big damage spells.
At 10 mana, play Aviana, then play Kun to refresh your mana. Now your creatures cost 1 mana. Play Malygos and then use your remaining 9 mana to spam your opponent with spells. If you have Prince, you can clone Malygos and your spells do almost twice as much damage.
This one doesn't require Kun or Aviana. Play Emperor to reduce Malygos to 8 mana, Prince to 2 Mana and Living Roots to 0 mana. Then the following turn play Malygos, clone with Prince and spam Moonfires and Living Roots. Each Moonfire does 11 damage and each Living Roots does 12 damage.
You can also make use of Innervate to cheat other spells into play with Malygos reduced or not.
Other than that just ramp as quickly as possible and draw as frequently as possible to assemble the combo(s) before dying.