If you are a mystic adept and choose a mentor spirit, and then choose the "Magician Powers" option, whichever adept powers you would have gotten if you had picked "Adept Powers" disappear off the list of chooseable adept powers in the magic tab under "add new adept power".
I'm not sure if this continues after locking the character for progression, but in character creation it does this and is very easy to reproduce for any/every mentor spirit and adept power listen therein.
I'm not sure if this continues after locking the character for progression, but in character creation it does this and is very easy to reproduce for any/every mentor spirit and adept power listen therein.