This is a game I had earlier tonight on Kulas Ravine where I had the high ground by Terrans base which he was unable to get to because of rocks. My understanding is if you don't have an air unit or a unit on the ramp you can't see the units attacking you. However, after watching the replay, once my stalkers engaged the siege tanks on the lower ground they became visible to the Terran player and he was able to hit them with his siege tanks. He didn't have any air units gaining him line of sight or access to the ramp because of the rocks. He was even able to reach my colossus that was at max range with the range upgrade that was also on the high ground. An orbital command scan wasn't used either.

My question is how was he able to see my stalkers and attack them without gaining line of sight? My understanding of how that works seems to be incorrect.

1 Answer 1


So your understanding of Sight and Line of Sight is correct, without any unit up there there is no way he can see or target your stalkers (even if you attack him, which was not true in SC1), unless he:

  • Scans
  • Has an Air Unit in the area
  • Moves a unit to the High Ground
  • Has a Xel Naga Watch tower
  • Your units move down a ramp
  • Your units are air units

Looking over the replay he does scan you at 14:08 to attack your stalkers at the high ground. At 12:16 he gains vision of your Colossus because it counts as an Air unit for purposes of vision.

  • 2
    I did not know that. I knew that Colossus are susceptible to air attacks but I did not know you could gain line of sight when they engaged a target that normally wouldn't have line of sight.
    – Mark
    Commented Aug 25, 2010 at 0:32
  • 2
    @Mark it is a little known fact as it only affects the Colossus and only in this Scenario. It was added in beta to deal with some of the ridiculous Colossus play at the time.
    – tzenes
    Commented Aug 25, 2010 at 1:02
  • thanks for the info. Had I known that before I'm sure I would have lost far less stalkers in that game but at least I still managed a win.
    – Mark
    Commented Aug 25, 2010 at 3:38
  • Never knew that tidbit about the collosi, but I can now imagine some nasty micro possibilities with the colossus if they weren't visible. Commented Aug 25, 2010 at 17:24
  • @Peter You still can. As long as an air unit is not attacking, it is invisible on high ground.
    – tzenes
    Commented Aug 25, 2010 at 17:37

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