2. House rule or sniper rule from S&S. I am thinking of basing the circumstance bonus on number of attacks....treating the arrows as tracers. The more tracers that are fired, the easier it is to pinpoint the attacker. (+5/attack to spot)
But what if she takes her shots and then moves 5 ft? That would not "pinpoint" her location. You may still know the general location, but I'm not sure a "pinpoint" after the shots take place and then a subsequent 5 ft. move is viable. I would see it more like a % chance to locate the character's location with some degree of accuracy.
-Drasmir (I love to argue with my DM
