I am currently playing a ranger and am wondering about Prime shot's closer than allies rule. If I can't see my allies, they can't see the target etc, how/what decides if allies are closer or not? Or, is it they are simply closer to the target on the grid right now?
Primeshot triggers if at the time of the attack no one is closer than you to the target
+1 bonus to ranged attack rolls against a target, if no allies are nearer to the target than the character. - PHB P. 104
Basically no one can be closer to the target than you, but they can be the same distance as you and you will still get the bonus to the attack roll. If its in combat on a grid count the squares. If it is out of combat you can simply use the distance between you and the target (30 feet for example).