Currently I am thinking about takink "Mark of Phaenonite" Elite advance.

My Psyker is someone who was found in stasis container and does not remember anything. he wants secretly to destroy universe (a backstory created for first time DH play and first in Warhammer universe. oh well. I kept it.) had much experiencies with daemons. Now he is 10 rank Primaris psyker (biomancy mastery and a lot telepathy) with alt rank tainted psyker and saboteur alt rank (just to explode things up while timefade for extra dickery)

So. I would like to get some ideas how to play phaenonite acolyte? What would my inquisitor tell me to do? how to keep it secret?

For fun , our group contains Sin Eater/Ordo sicarius PC and everybody are with major mutations.

Please, help. It is somehow troublesome to get the idea how to play phaenonite

The phaenonites are conspirators that wants power and control. They do not do it for the Imperium, even less the Emperor.

They are, supposedly, concerned with getting off the shackles that actually enslave mankind. So we are speaking about megalomaniac that think that they can do better than the rest of mankind and use the warp and other xenos tech as tools for their objectives.

They are madmen.