During this whole month, you’ll be able to earn Challenge Points, while unlocking chests to obtain some sweet loot. The Saddled Terrorbird is the mount this month during the challenge. You’ll see an above-average base move speed. You’ll also see an invincibility/speed burst spell.
There’s also a new Carnival Challenge Avatar ring to unlock. You’ll get this ring once you hit your challenge point goal for this month. This is a non-tradeable item which permanently unlocks for one of your characters. Alternatively, you can trade this at the vanity merchant.
Finally, seasonal specials were outlined which include Adventurer's Tomes, resources, and silver bags. There’s also carnival themed wardrobe skins and new furniture items. If you’re interested, you’ll be able to log into the game and start earning your challenge points.
In case you missed it, the devs recently discussed the Call to Arms update. You can learn about that here.