The Winter Evolving Buildings are some of the most important rewards you can win in the event! Check out their individual pages in the community wiki run by players like you:
In addition to the Evolving Buildings, you can also win Customizations. Those are modifications that you can apply to your existing city buildings to temporarily change the way they look and increase their output or add extra production, like for example goods or Research Points!
Avatars
The event comes with special festive avatars that you can get and apply in your player profile if you complete all the quests:
Other rewards
In addition to all the above, you can also win Items and resources! Items are single-use consumables that provide you with immediate effect. Among them, you will find Refill Items, as well as Age Up Kits, Selection Kits and Mercenary Commanders.