How does the Multiple Attack Penalty apply to the Chain Reaction feat?

Question

The Chain Reaction feat available to the Unexpected Sharpshooter dedication allows a character to, as a 3-action ability, make a shot, and then make additional strikes against new targets as long as each successive strike does not miss.

You fire your gun once, creating a devastating and unpredictable chain of events; perhaps your bullet strikes exactly the right spot on a water tower, causing it to flood and incite a stampede of horses which knock over a lantern that sets a city on fire. Whatever the exact chain reaction, and no matter how improbable, the indiscriminate catastrophe creates significant challenges for your enemies across a wide area while leaving everyone else alone.

Make a Strike with a ranged weapon, and if you hit, you can make another Strike at a target within 30 feet of the first target. If you hit the second target, attempt to Strike a third target within 30 feet of the second target, and so on, continuing until you miss a target. You can cease the chain at any point; otherwise, it ends when you first miss an attack. However, you can't target the same creature more than once; each time you move to a new target, it must be a target you haven't made a Strike against yet during this particular use of Chain Reaction.

This damage is caused by some improbable set of events that injures one target after another, rather than from actually making several shots. Perhaps you shot at a tree branch that then fell on the targets, or one target's scream caused another to accidentally set off their gun and shoot themselves in the foot. This means that only the first target suffers any special effects tied to the bullet (if it was magical ammunition, for example), but each target you hit still takes the same damage dealt by your Strike. Normally, all damage is of the same damage type as the initial bullet. However, the GM might choose to change the damage type based on their description of the chain reaction. For example, if one target was burned by fire, that target might take fire damage instead of physical damage.

Unlike many similar abilities, there is no language indicating one way or the other as to whether the Multiple Attack Penalty (MAP) increases between Strikes within this activity. Is the MAP applied to each successive strike in the chain? Does it only count for the one initial strike? Is it increased for each strike in the chain, but only after all strikes have been taken? (i.e. if the chain reaction hits two or more targets, MAP would be at maximum for any successive strike, but all Chain Reaction strikes would be at no penalty).

Answer 1

Exceptions need to be mentioned

Since this is multiple Strikes, then MAP applies normally to each individual Strike in the chain. While many abilities do explicitly address MAP, some don't (like Two-Weapon Flurry). The abilities that say to apply MAP say "as normal", like Flurry of Blows or Hunted Shot. So, clearly the normal case is to use MAP for each Strike, and since this ability doesn't call out an exception, it should use the normal case.

Solving the Narrative

Admittedly, the problem here is probably only because, narratively, this is all caused by one bullet (however improbable). Stripped of all flavor text, this problem doesn't really arise. There are probably multiple ways to make the narrative match the mechanics, but here is how I would think about/narrate it:

MAP is a mental tax as well as a physical one: it's not just harder to swing your sword more, even aiming precisely is harder - finding many openings in 6 seconds is difficult, let alone ones that are as creative as Chain Reaction calls for. MAP represents how much harder it is to find the necessary opportunities for each successive target. The important thing here is that *these are intentional consequences of your shot, and it takes your thinking time and capacity to stretch them further.

Conclusion

You'll apply the normal multiple attack penalty here, so presuming you haven't already made an attack this turn, your first Strike will have no penalty, your second Strike will have a -5 penalty, and your third and later Strikes will have a -10. (These can be reduced by things like Agile, or perhaps more relevantly the Flurry Hunter's Edge).