I thought it was saying that form the Low Ground You can see 1 less up the Ramp, in some cases i have seen stalker been able to Blink onto the High Ground from the Low ground without Vision.
This is actually what I'm not sure of, whether it is low ground to high ground vision for units on ramp to high ground. Though I'm pretty sure that low ground doesn't have any vision of high ground, so it should be ramp to high ground vision. I'll wait until Blizzard or someone here clarifies this.
Also it's impossible to blink without vision, they probably blinked onto the ramp or had an obs somewhere.
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