Q: Is a model equipped with the Scrolls of Magnus that does not
begin the game as a Psyker, considered to have become a Psyker once
they acquire one or more additional psychic powers from the scrolls?
For example a Dark Apostle with the Mark of Tzeentch. (p69)
A: Yes, the model has the Psyker rule from that point
onward, and is considered to have Mastery Level 1.
Gut, das FAQ macht ihn dann tatsächlich zum Psioniker. Sonst währe es nicht möglich.