Guild Wars 2

Where is the achievement or recipe for this?

https://www.reddit.com/r/Guildwars2/comments/3pvy71/nightfury_the_new_bat_shoulders_first_step_done/

Ok, so my only goal for the next two weeks are these kitten shoulders, and I have spent the last couple of hours toiling away at it.
The first step to get “Bat Wing” is thus:
4x Tattered Bat Wings
250 Mystic Coins
20 Bloodstone Bricks
120 Powerful Blood (might have been more, was just excited I got the 4th item)
Now….I have about 75% of items in the collection category…and have bought almost every new item from HoT, and all the items but the pets on the CC Vendor…and kittenall lights up when you put the Bat Wings into the forge…Community – Go!
Update: So “Bat Wing” combines with Glacial Lodestone….and 2 other somethings. Also, Endless Bottle of Batwing Brew can combine with Vision Crystal and 2 somethings, which is likely (but not guaranteed) to make it part of the components for this item.
Rather important note: Made a Second Bat Wing, just to test if you needed 2+, they do not light up together in the forge…so do not make more than one.

Edit: new informations.