ok this is the path i have that gets 3 stars. its not pretty but i hope it makes sense.
the golden dot is where you start. the blue dots are the other enemies
The Red Lines is the first steps before killing the first summoner
The Purple Lines is the pathway after you kill the first summoner
The green lines is the pathway after you kill the second summoner
Lots of backtracking on this level. hope it helps
Note: the two dots you see are left alone on purpose, from what i have found if you take either of them at any point you automatically can no longer get 3 stars