What ballpark range do you need to be to take Shadow Empress down

That's a terrible way to consider DR, though, at least for timing purposes. You should be counting 80 seconds from when it starts, not 65 seconds from when it ends, since, it doesn't seem to happen that often now, but the icon for DR lingers a bit and if you count 65 seconds from when you stop seeing it, you'll probably attack into the next DR.

I always use Elite Puppet and Phoenix to check when DR ends because of this. You end up with the same problem in reverse since there's a delay before the icon appears as well.