Wand with a spell and the hero's line of sight.

SetWarfogBehaviour(0,0)

function SetHeroLookRange(hero, range)
print(Range)

while 1 do
  local x,y,fl= GetObjectPosition(hero)
  OpenCircleFog(x,y,fl,Range, GetObjectOwner(hero))
  sleep(0.1)
end;
end;

startThread(SetHeroLookRange, "Hunter", 6);