Someone on reddit seems to have discovered a curious interaction between the Barbarian and Ranger abilities, which seems like something that should probably be patched out (assuming I'm not missing something as to how it works).
- The ranger has the feat 'Disrupt Prey', which works similarly to attack of opportunity, but only against their chosen target and as a free action.
- The barbarian has the feat 'No Escape', which allows them to follow an enemy that tries to leave their reach as a reaction.
- One of the conditions for Disrupt Prey is 'or leaves a square during a move action it’s using.' (while it is within your reach).
- No Escape makes it clear that you are moving with the target, not after them, and that they remain within your reach at all times.
- While only one reaction or free action can trigger at a time, a creature that strides 25 ft is leaving a square on five separate occasions, possibly meaning that they create five separate triggers.
- On the first trigger, the Ranger/Barbarian uses No Escape, remaining in reach of their prey for the remainder of the move. The prey then leaves squares four (or more, if the Barbarian can keep up with them!) times, each time triggering the free action Disrupt Prey. (They may be able to stop after they start taking hits - do you need to confirm where you're moving to before you Stride?)
This requires the target to be designated as the Ranger's prey, which has a Concentrate tag, but I don't think there's anything saying that, once designated, a creature stops being the Ranger's prey if they can no longer concentrate.
Is there a rule I'm missing here that prevents this?
The 'or leaves a square as part of a move action' was the key part of the concept they presented, but I have since found the passage in the book that clarifies that it only happens once anyway.
Disrupt Prey is almost 100% certainly meant to be a Reaction. It has almost identical wording to the Monk's attack of opportunity replacement, which is a Reaction. It's meant to be more specific than attack of opportunity, because Ranger is not Fighter. In the same way that the Monk version is different from the Fighter version.
Most of all, being able to attack as a free action would not fit the design philosophy evident in the entire rest of the game.
And, as Deadmanwalking mentions, Snap Shot is a dead feat if Disrupt Prey isn't a reaction.
At one of the streamed panels from Gen Con, Mark Seifter specifically called out that Disrupt Prey was meant to be a reaction and not a free action. I'd suggest treating it as such as there will be errata for that in the near future.
I have no link, but it should be on Paizo's twitch channel and I believe it was the PF2 Rules Q&A seminar.
As in PF1e, I think Paizo kept the rules about movement triggering AoO's. Which is what makes the Warrior Poet's ability Petals in The Wind to not be overpower. Movement will only trigger once and maybe you can land a single Disrupt Prey... At best.