Unknown Items listed at AllakhazamFollow

Not sure, but I know in (CENSORED) XI, it was possible to look through the coding of the game (there were programs to do this) and to identify new abilities not yet implemented in the game, such as Hastega II or whatnot. Sometimes these abilities were only possessed by enemies; other times they were thought to be "unlocked" in future updates.

I don't see why WoW isn't the same. At any rate, thottbot.com doesn't show the elemental transmutation recipes, but we know some exist (you can get one from the Argent Dawn, for example). It can be that they taught abilities and scrolls of them are not sold, or something like that.

I can think of a few reasons how something can exist without a recipe ^_^ Also, some items (like the translation potion) were coded in, or in Beta, but never put into the live version. Some, like (I believe) a Frost potion were part of a holiday deal, and removed afterward.