Feather Zone is an individual instance where you can obtain Star Feather, which are needed if you want to upgrade your wings. There are generally several Shrine Jokers that need to be defeated before the BOSS, Shrine Sprite, of the instance appears.
Earn EXP and Star Feathers. Use the Star Feathers to upgrade your wings.
You may attempt it three times per day.
To initiate the instance, talk to the Goddess Priestess in Lunaria City. Select the correct option (middle option, "Feather Zone [Single]"), which will only appear when you accept the latest Star Palace Ruins quest.
The instance itself is fairly easy to follow if you afk.
Feather Zone is relatively easy, especially for higher levels with a higher might.
The Shrine Jokers are relatively easy to defeat as they have medium defence (mdef/pdef) and attack (atk). Shrine Spirit has a higher defence and attack more strongly than the Shrine Jokers, but they are still relatively easy to defeat. The Epic Shrine Spirit (usually Shrine Spirit (Heroic)) appears randomly after defeating the normal Shrine Spirit, having higher defence and attack from the normal Shrine Spirit, but drops more rewards.
There is a fifteen minute time limit, but most people are able to complete it before then.
Shrine Jokers award around 250 EXP each (no World Level EXP Bonus), which Shrine Spirits award around 2250 EXP each. This is relatively a lot compared to other instances/
Shrine Spirits drop around 1-3 Star Feather, though usually just one, while Epic Shrine Spirits tend to drop an additional 2-6. Shrine Jokes also randomly drop Star Feather, but the drop rate is low so not many Star Feathers are gained from them.