1 bag of caltrops covers a 5 foot square and makes an attack roll 1d20+0
Does the number of attack rolls increase based on the distance traveled?
for example a 20 foot hallway covered in caltrops results in four attack rolls for a person covering the entire distance.....
Each time a creature moves into an area covered by caltrops (or spends a round fighting while standing in such an area), it runs the risk of stepping on one. Make an attack roll for the caltrops (base attack bonus +0) against the creature.
So is it each 5 foot area?