Ok, first off u will occasionally will have a huge loss when farming lv 10 npc.. it just happens, no obvious reason for it. I will say that using corselet and war horn will help w losses. Also there is no reason to scout prior to hitting a lv 10. I have had bigger losses on lower lv hero's than on high lv hero's. U have to think of it like your feasting hall. U may come across a great attk hero w a low lv and then another hero w a high lv will have crappy numbers. The same goes for farming npc's. Just my opinion.. Happy hunting!