Modifiers:
The 2-circle intersections defend with +1 when attacked from a 'home-base' circle.
There are 2 territories that are the result of a 3-circle intersection. These defend with a +2 against the 2-circle intersections that they are adjacent to.
Bonuses:
Each complete 'circle' or 'ellipse' is worth a bonus equal to the number of circles/ellipses that intersect it.