I created a custom ruler and chose the perk that gives you free recruitment of champions. As a weakness I also chose the perk that gives you +1 attack and champions cost 50% more to recruit.

Now, 50% of free is still free so I took these perks to see what the game did with them. As it turns out, the champions are not free so the "free champions" perk seems to be ignored. Since this obviously is a wasted perk pick, shouldn't the game not allow you to choose both of these perks at once? 

On the other hand, if the champion recruitment cost I'm seeing is reduced or prorated somehow from what it would have been without taking the "free champions" perk, the game should show that somwhere. There's no way to tell how these two perks work together currently.