I have an zen archer monk and I am trying to figure out the exact rules for ranged grapples. Here is the research I have.
Grapple Description on Weapon Page (scroll way down, search grapple #19/21)
Grapple: On a successful critical hit with a weapon of this type, you can grapple the target of the attack. The wielder can then attempt a combat maneuver check to grapple his opponent as a free action. This grapple attempt does not provoke an attack of opportunity from the creature you are attempting to grapple if that creature is not threatening you. While you grapple the target with a grappling weapon, you can only move or damage the creature on your turn. You are still considered grappled, though you do not have to be adjacent to the creature to continue the grapple. If you move far enough away to be out of the weapon’s reach, you end the grapple with that action. Source: Ultimate Combat.
When a barbed arrow is attached to a length of silk rope and fired from a bow, the arrow’s range increment is reduced to 30 feet, but it gains the grapple special weapon quality.
So, using special equipment allows you to make a ranged grapple attempt as a free action on a critical hit.
First question, because other weapons add their bonuses such as enhancement values to CMB rolls such as trip, the same should also hold true for the grapple attempt?
Second question, on future rounds after a grapple was successfully performed, does the weapon bonus still apply to grapple checks?
Third question, do weapon special properties such as flaming apply when you decide to deal damage during the grapple?
Forth question, how does the grapple attempt affect future attacks in the round? As a zen archer I will be making multiple attacks and any of them could be critical hits. If my first attack is a critical hit and I am successful on the CMB check, what happens to the rest of my attacks in the round?
Fifth question, I take it that because both of us have the grappled condition, the normal actions involved for grappling apply. So start of round check to maintain grapple, then I can pin or damage, …
Sixth question, because the range increment is dropped to 30 feet, does it still allow up to 10 range increments? Im assuming that its because of the weight of the rope which gives the greatly reduced range increment, but shouldnt there be something about the length of the rope?
Seventh question, what action is it to attach a rope to the arrow?
Eight question, is CMB and escape artist the only way to escape from this grapple, or could someone cut the rope, break the arrow, …?
Fighter Archetype Archer
At 11th level, he may also choose from the following combat maneuvers: bull rush, grapple, trip. A target grappled by an arrow can break free by destroying the archer’s arrow (hardness 5, hit points 1, break DC 13) or with an Escape Artist or CMB check (against the archer’s CMD –4).
Best Answer
The barbed arrows are woefully underwritten. Further, the special weapon feature grapple just doesn't play well when applied to ammunition.
Attaching the silk rope to the barbed arrow
According to barbed arrows, "When a barbed arrow is attached to a length of silk rope and fired from a bow, the arrow’s range increment is reduced to 30 feet, but it gains the grapple special weapon quality."
How exactly an archer attaches a length of silk rope to a barbed arrow is a minor mystery. In Pathfinder's antecedent dnd-3.5e, an archer would employ the skill Use Rope, a skill Pathfinder thankfully deleted yet did not neatly replace. As binding a foe is based on the binder's Combat Maneuver Bonus as per the skill Escape Artist and a grappler can take a standard action to tie up a pinned foe, presumably an archer can take a standard action to attach a length of silk rope to a barbed arrow, but this is speculation.
Attacking with a barbed arrow that has a silk rope attached
After the silk rope is attached, an archer lets the barbed arrow fly. On anything less than a critical hit against his foe, the archer deals normal damage. On a critical hit against his foe, the archer deals his critical hit damage and can take a free action to make a grapple attempt… despite the typical barbed arrow (like most ammunition) "that hits its target [being] destroyed or rendered useless" and the stubby length of the attached silk rope.
The archer must take that free action to make a grapple combat maneuver after the archer's dealt that critical hit damage else lose the opportunity to do so, but from there, the archer obeys all the rules for the special weapon feature grapple and the rules for executing the combat maneuver grapple. To put this in context, here's the combat maneuver grapple rewritten so that an archer can use it when he makes a successful critical hit with the barbed arrow:
(Emphasis mine.) In other words, if the archer succeeds on that grapple combat maneuver, the archer pulls the foe adjacent to the archer then can opt to either continue the grapple or take a free action to release the grapple.
Now, I deliberately don't use the word clearly very often, but clearly the vast majority of archers do not want foes adjacent to them! I can only assume the (ahem) point of barbed arrows is not to grapple a foe, drag the foe adjacent to the archer, then have the archer proceed to rassel the crap out of that foe—most archers aren't just aren't specced for that, and giants that do this to PCs straight-up murder those poor PCs.
However, that's what happens. I mean, the weapon quality grapple says, "While you grapple the target with a grappling weapon, you can only move or damage the creature on your turn," and that makes sense, but then it continues, saying, "You are still considered grappled, though you do not have to be adjacent to the creature to continue the grapple" (emphasis mine), but that means a creature that's using a weapon with the grapple quality must still be adjacent to a foe to start the grapple! Then the description finishes, saying, "If you [in this case, the archer] move far enough away to be out of the weapon’s reach, you end the grapple with that action."
In other words, the special weapon feature grapple functions fine on reach weapons and other melee weapons that hook a foe, drag the foe over, and then allow the attacker to move away from the foe within the weapon's reach, but with a ranged weapon? Yuck. I mean, what's the reach on an archer's arrow? The archer's natural reach. What's the reach—not range increment, mind you, but reach— on an archer's bow? 0 ft. What's the reach on the archer's barbed arrow that's destroyed because it successfully struck a foe? That'd be a flat nothin'.
Questions and Answers
In short, not a whole lot of this makes sense. Keep this assessment in mind while I take each question in turn.
This GM strongly urges a house rule saying that an archer that makes a successful critical hit with a barbed arrow that has a silk rope attached instead renders his foe entangled much like a net, the archer controlling the trailing rope if the silk rope attached to the arrow is sufficient to span the distance between archer and foe and if the archer is willing to commit a free hand to the task.