How does the Darkvision ability (or spell) work beyond range? A lot of creatures have Darkvision: range 60 feet. Does darkvision simply stop working past there? Do you get penalties to sight-based checks (or aiming ranged weapons) past 60 feet?
Let's take a hypothetical straight, infinite tunnel that's pitch-black. A kobold with darkvision: 60 ft is standing in the corridor. Does it:
A) See perfectly for 60 feet, then there's a wall of blackness that it cannot perceive past. A creature standing exactly 61 feet away is perfectly concealed.
B) See perfectly for 60 feet, then starts taking range penalties every 60 feet after that. so a creature standing exactly 61 feet away has a -2 to be seen, a creature at 121 feet has a -4 to be seen, etc.
C) Some other option I hadn't foreseen.