I am referring to the mystic class presented in Unearthed Arcana. As far as I know it's not a prestige class like the rune scribe.
It only had the levels 11-20 in the third iteration
[T]he class now goes to level 20, has six subclasses, and can choose from many new psionic disciplines and talents.
1: Note that the article has been updated to link to the second version.