When you level up to Lv46 and complete relevant main quest, you will unlock it.
Click the Bag and open the Retinue Card Interface then you will see the icon of Land of Chaos.
The Main Interface as follow:
Players can challenge Retinues in this place, click to combat, if you win, you can acquire random number of Retinue Card Shards. There is a possibility to obtain a Retinue Card.
The Rare Retinue (Whose name in Purple or Golden) will offer more Retinue Card Shards.
*Retinue Card Shards can exchange for Retinue Card in the Retinue Card Handbook. After exchanging, the Retinue Card will be sent to your bag.
If you fail, you need 30 seconds to revive and you can’t move during the Revive. You can also spend Gold on reviving immediately. You can do next challenge after waiting 15 seconds.
During the event, Retinues will refresh every one hour and there are 30 Retinues each time; (The Retinues will disappear if you don’t defeat them in the last wave)
Players have 15 challenge chances for free every day, it will be deducted if you succeed in defeating Retinues (If you fail, it won’t be deducted.) You can also use Gold to buy Challenge chances. The Challenge will be reset whether you have used them up or not.