I started a 2v2 comp-stomp last night with my roommate. I'm playing Advent, she's playing Vasari, and we have a Peace Treaty. Since I'm generally fond of the subtle benefits of culture, I throw up a couple Broadcast Centers and watch with glee as my influence begins to creep down the phase lines.
Then I notice that when my culture starts creeping into my ally's territory, the allegiance ratings on her planets begin to rise. My roommate's not playing with culture--all of her allegiance values on the planets my culture isn't touching are still at their base values--but she apparently doesn't need to bother with culture at all, because as my ally, she seems to be sharing the benefits of mine!
. . . now I really want to know how far this goes. If she's fighting a battle in my culture, does she gain the benefit of my Advent shield mitigation bonus? Or does she get her Vasari damage bonus instead? If the latter, does the percentage of her damage boost scale with her culture research, or mine?