I gave your method a try with 6 normal heroes at level 100 and a queen at 100. There was one of the later archer waves that was wiped out with no report. I have to say this is an incredible guide and if people follow it closely but have some extra troops for unexpected results then getting a 12 should be very easy. I did never achieve the number of troops kills listed, I am guessing hero gear had a lot to do with that.

Again, this is an incredible guide that makes it possible even for people starting after all the historical heroes are gone to capture historical cities.