At least 10 units? Lol, you may damage about 8 units... But SS does 150 damage for 65 mana which may kill one. What good is damagin units other than killing them, that's why focus firing is good. Because if you don'tt focus you damage many units for same damage maybe more if you have to run to get them... but you actually put units out of the battle, which is very effective if you take the hero out.