Eg, 20 posts AND 20 likes get you a promotion to a usergroup "Awesome member"
It would be good to have a option next to each conditional to select each condition as an OR statement aswell.
So, 20 posts OR 20 likes gets you a promotion to usergroup "Awesome member"
Otherwise, you end up with 2 or 3 different ways to join a usergroup, which would require 3 different promotions, when realy, they could be handled by one.
It also adds in more flexibility, eg
You require 20 posts OR 20 likes AND be registered for 30 days to get promotion XYZ.