This is a prestige class I created for my PC in an ongoing in-person Pathfinder campaign. In that world, it is the signature class of a world-spanning espionage network. It was originally a 3-level class based on the Vecna-Blooded template, expanded to 5 and then to the full 10 over time. I expect it is slightly but not overwhelmingly overpowered.

Masked Eye

Knowledge is power. To spies, this is the basic premise of their trade. To priests of Vecna, it is a holy truth. To a Masked Eye, it is a philosophy of life. To know everything about others, and prevent anything being known about yourself, is the ultimate achievement. Tracing their line to an apostate Vecna-blooded cleric who stole the secrets to gift to his personal espionage network/cult, the brotherhood of Masked Eyes considers all secret knowledge in the world theirs by right.

Skills: Bluff 6 ranks, Disguise 6 ranks, Knowledge(nobility) 6 ranks, Perception 6 ranks
Feats: Skill Focus(Bluff)
Special: Must be inducted into the class by another Masked Eye or by a Vecna-Blooded.

Hit Dice: d8
Class Skills: Acrobatics(Dex), Bluff (Cha), Diplomacy (Cha), Disable Device (Dex), Disguise (Cha), Escape Artist
(Dex), Knowledge (all) (Int), Linguistics (Int), Perception (Wis), Sense Motive (Wis), Sleight of Hand (Dex), Stealth (Dex), and Use
Magic Device (Cha).

Skill Points: 6+Int per level


1st|+0|+0|+1|+1|Enigma Aura 1/day

2nd|+1|+1|+1|+1|Cloak of Mystery, Sneak Attack +1d6

3rd|+2|+1|+2|+2|Fade, Vanishing Enigma

4th|+3|+1|+2|+2|Cover Tracks(1/week), Sneak Attack +2d6

5th|+3|+2|+3|+3|Enigma Aura 3/day

6th|+4|+2|+3|+3|Blend, Sneak Attack +3d6

7th|+5|+2|+4|+4|Enigma Mind

8th|+6|+3|+4|+4|Cover Tracks(1/day), Sneak Attack +4d6

9th|+6|+3|+5|+5|Vanish, Enigma Aura At-will

10th|+7|+3|+5|+5|Perfect Cover, Sneak Attack +5d6 [/table]

Enigma Aura (Su): Once per day, as a standard action, a Masked Eye can wrap themself in an aura that makes creatures within 120 feet intermittently forget that they're there. At the start of each affected creature's turn, that creature has a 50% chance to be unable to attack the Masked Eye in any way, including with spells and special abilities. The aura lasts for 1 minute after it's activated.
Chosen allied creatures can be excluded from this effect at the Masked Eye's option, at the time of activation. At 5th level, the Eye may activate this ability three times per day. At 9th level, the Masked Eye may activate it at will.

Sneak Attack: As the Rogue ability, gains an additional die at each even level.

Cloak of Mystery (Su): Knowledge of the Masked Eye fades from the world. Its original name, its deeds before entering the class, and so forth, fade from memory. The Masked Eye themself retains full knowledge, as does the Eye who administered the ritual. Allies who spend significant time interacting with the Masked Eye keep approximate knowledge of the Eye and their deeds, but recorded knowledge and knowledge in the memories of other creatures fades and becomes difficult or impossible to recall. (DC 30 Int check to remember any fact other than name about the Masked Eye. Only other Masked Eyes and creatures which have directly interacted with the Eye can make this check; non-Masked Eyes take a -1 penalty for each month since their last contact with them. Other non-divine entities can't even attempt the check.)
A Masked Eye with Cloak of Mystery gains immunity to all divination spells cast against them or cast to learn information about them. Such divination fails to reveal any information. The Masked Eye immediately learns the name, appearance, and location of the caster who attempted the divination. Deific magic or magic of similar power ignores this effect; it succeeds and does not alert the Eye.

Vanishing Enigma (Ex): While under the effect of Enigma Aura, Masked Eyes can make Stealth checks as though unobserved, as Hide In Plain Sight.

Fade (Ex): The color fades from the Masked Eye's body and distinctive physical traits become less obvious. This grants a +4 bonus to Stealth while in shadowy illumination, or a +2 in darkness.

Cover Tracks (Sp): Once per week, the Masked Eye may cast Modify Memory with caster level equal to the Eye's character level. At 8th level, this may be used once per day instead.

Blend (Ex/Su): (Ex) All distinctive features of the Masked Eye blur into unnoticeability. They permanently appear as a generic member of their race with muted colors. (Su) Additionally, the Eye can mold their form to match chosen shapes. 1+Int modifier times per day, the Masked Eye can assume the form of another humanoid or monstrous humanoid of the same size or one size smaller. This emulates /alter self/, except that the Eye may assume the appearance of specific individuals. While in a false identity this way, the Cloak of Mystery does not protect the Eye; only once they are discovered does it become difficult to remember their disguised actions and appearance.

Enigma Mind (Su): While under Enigma Aura, the Masked Eye is immune to mind-affecting effects.

Vanish(Su): The Masked Eye has lost so much of what makes them an individual that the world itself no longer properly recognizes them. The permanently gain the shapechanger subtype, and if previously a humanoid gain the monstrous humanoid type. They no longer need to eat, drink, or sleep more than a few times per year, and do not age; they will not die of natural causes, though they may still die of violence, disease, poison, etc. They may qualify for classes, feats, and items as though they were a doppelganger.

Perfect Cover (Ex): A Masked Eye is proficient in all weapons, armor, and shields called for by the Eye's current disguise, and can use any spell trigger or spell completion item as if the spells were on its spell list, with caster level equal to Eye level. On any skill check related to a current or recent disguise, the Eye may make a check as though they had ranks in that skill equal to half their Masked Eye level (If they have more ranks than this, no additional bonus).