How do cards that grant a card bonus ( I.e void pirate) work? Thanks.

http://www.cardgamedb.com/index.php/wh40kconquest/conquest.html/_/core/void-pirate-r181

If you win a command struggle at a planet where one of these allies is present, then you get not only the planetary bonus, but whatever bonus the allies give added on. In the case of the Void Pirate, is +1 card added to however many the planet would have given you..

You have to win the command struggle though?

Yes u do

That makes sense. Thanks a lot.