It should be a pass in the cashshop that you buy for 20 bucks and with this pass you're allowed to take on an event ingame. It's fate farming. Minimum 1500 fates. If you're unlucky (drop rate of needed items will be low) you might have to do more fates. Once you get all the items you can turn them in for A HALF of the wings. The second half needs another pass that you need to buy. You can't equip only one half so u definitely need to spend 40 bucks in total. The outfit you get for an additional 20 bucks. Only equippable if you have the complete wings.
Now that's what I call good content!