I actually had the idea for this months ago but was never in a position to test it out until 47 opened. Keep in mind the hero is a 0 set hero and med and iron working are still at lvl 8. Now DO NOT try this unless you or sombody else in this thread manages to figure out how it was done with so few losses. If nobody figures it out in a week or so I will reveal it. If you try it normally you will loss much more. This is the very first time this type of wave has ever been sent with so few losses to my knowledge but if anyone has allready done this feel free to correct me. Using this you can farm a lvl 10 npc anywhere within 100 miles in 30 minutes if you send straight 125k cav for just abit more losses.
Edit: Apparently its known. Just not quite sure why its not used more often considering its both faster and more efficient troop wise.