The range of the spell is indeed 6sqms, from the sides that would mean 1 square away from the limit, and from north and south that would mean as long as you see it, but it can only turn up to 3 creatures into melee fighters. The cooldown is only 2secs though so the limit of creatures shouldn't be an issue imho, also unlike the paladin version of the spell this one does indeed challenges (taunts) them, so they would go for you, can't be used on bosses tho!