Actual visual is 6 tiles, because helmets, but whatever.
The check happened at 12 (if log is correct) or 11 tiles (closest).
Also may explain why spellcasters w/o a set spell range are so annoying. Because they can cast 12 range at least. Like the necros do, for example.
Necro proceeds to cast his spells at range 9 (topmost corpse) & from beyond the monolithic tree wall.
Fails to break the line, feels insecure and decides to run away.
LuuuuL.
And yeah, casters totally need their vision & range checks to cast their spells >_>