Dare to say

Unspeakable

Prestiges 1-2: (works everywhere):

“Hush”

“You know who” - During each month instead of one scroll you may give out a scroll of each kind (Ascended, Hero, Champion) for this character and chosen assistants
"He-Who-Must-Not-Be-Named" - The first time your name is invoked (spoken, written, or otherwise mentioned) on a quest that creature that invoked the name is transported to Axiom or leaves the quest, DM’s choice. If said your name for a second time, the creature dies and is erased from existance (even if not a deadly+ quest, the creature dies)

Association

Prestiges 3-4: (Works in native realm and realms where you have roots.):

Works from the shadows? If only worked at all

Axiom Rumors - While running a quest in Axiom, the DM may bless the monsters or the party
Not Ready - While running a quest in Axiom, the DM gains inspiration die which can be used to re-roll any d20 (including player or monster alike)

That which does not exist

Prestiges 5-6: (Works in certain parts of the native realm):

You saw nothing 

That which should not exist - You do not get called instead if you are ever summoned, a poxy is summoned instead. You choose the statblock of the proxy which can be any approved creature or summoned.

Axiom’s Other Side

Prestiges 7-8: (works in domain or with explicit DM approval):

Never

Never seen again - Anyone who sees you is permanently killed