"Improved" True Name

[The Imperator]

Long story short, my wizard has hit 17th level, and instead of taking just another feat, I asked my GM if I could take True Name again, but instead of a new creature buff the current creature I have currently with True Name (taken at 15th level).

He said if I could find a template and come up with an in character reason for both entreating the outsider to undergo some process and for why the outsider would go along with it.

I currently have an Uinuja Azata, I am CN, and am a wizard focused on gaining knowledge/taking down Cheliax. This is a post-Campaign Skull and Shackles game.

So my question is what templates would be within the power level, I would think bumping up 2, or 1 if it's flavorful, CR for the Azata.

HD advancement is probably on the table too, but limited to the same limitations from my GM. My character's end goal is to create either a highly powered outsider/Empyreal lord to balance out the fact that our party helped a demon achieve nascent demon lord status to repay a debt we owed the demon. I don't intend to have an Empyreal Lord bound, that's just the in character end goal of this process.

[Lady-J]

advanced plus either holy or unholy based on the outsiders alignment would be the templates and in character reason, you have the true name of the outsider but it hasn't been revealing its true forum and now it is, if they ask why point them to anti paladin which can grant templates to their outsider follower

[The Imperator]

Thanks for the suggestion!