Looking for games with secret recipes

I am looking for mmo games that have secret recipes or secret ingredients which players need to discover and it is not written somewhere on the wiki. Once you find secret formula you can craft specific items or potions only known to few people.
I am interested in those games because i like playing as trader in games and secret recipes is what I consider the next level of trading.

Psst over here, shhh, keep your voice down, let me disclose some information of the... most arcane nature to you friend:

Those shrewd and well informed mystagogues, the ones savvy in the mysterious ways of both natural and metaphysical doctrines, tend to keep those occult recipes... secret, you know, for various reasons, that might, or might not be beyond common understanding. The fact that they are the most coveted and precious treasures, one can ever hope to get one's hand on —even within the premises of a virtual game world— is not exclusive of other more... mundane motives, such as the simple —yet undeniable— truth, that when a secret is revealed to everyone, including the masses of the common plebs, it stops being... secret. Usually it becomes common knowledge. Not that there's anything wrong with common knowledge, of course!