The new Druid deck is based around two cards: Embiggen and Frizz Kindleroost. It also has a lot of big dragons.
Embiggen gives all minions in your deck +2/+2. But it also makes your minions more expensive by 1 mana. You can also play Frizz Kindleroost and make all your dragon minions cheaper by 2 mana. As a result, your minions receive a buff and cost 1 mana less.
This combo is very powerful. With all the ramp cards in this deck, such as Breath of Dreams and Nourish, you will be able to play all of your big dragons early.
Be sure to play the new Ysera, Unleashed. The card can potentially put seven free dragons on your board. This legendary card from Descent of Dragons is one of the most powerful class dragons in the set.