The key words are Swift and Next Attack
Swift Actions
In D&D3.5e, you may only perform one swift action per turn, even if it is a mental action. So, you would only be able to activate Dislocator once per turn, at the most.
Next Attack
Multishot and similar abilities and effects produce additional projectiles as additional attacks. When you're firing two arrows, you're really making two attacks. So the one you designate as the "first" attack will be the "next" attack for Dislocator. Even if you could activate it more than once per turn, you'd have to activate it before each attack, meaning it would have to be in-between the arrows produced by Multishot, which isn't possible.
I really liked this question because of the idea of the idea of hitting someone with so many arrows that they poof and appear in the air, but unfortunately, it's not possible with that set up. Alternatively, you could hire four wizards of sufficiently high enough level to simulate the effect in battle.
"Look at what my arrows did!"
The four wizards are high-fiving each other in the background while looking mentally exhausted.
Edit: One thing I neglected to mention is that Dislocator mentions your next "successful" attack. Meaning that if your first three arrows miss and your fourth arrow hits, they would have to make a Will save. Still, you cannot force your opponent to make more than one Will save per turn in this way.
Rules-As-Written, you can't catch an arrow that is aimed at another
Your quoted text is pretty explicit about it, you have to be the target and you have to get hit in order to use the feature, that means if the attacker misses, you can't use Deflect Missiles.
On the Readied Action question, it wouldn't work either. Two things:
- Deflect Missiles is a Reaction, you can't ready a reaction.
- Even if you could ready a reaction, you'd spend 2 Reactions; one to trigger the Ready, and the second to Deflect Missiles.
"Alright, daze, but I really wanna do this cool thing!"
There are ways to kind of, sort of do this:
- Multiclass into a Fighter and get the Protection Fighting Style . Problem is, you'll need a shield to use it.
- Get your hands on a Shield of Missile Attraction. Attune to it and get cursed. You now attract any missile being fired at any creature within 10 feet of you. Remove the shield (you can't unattune to it according to DMG 139: "Cursed Items"), removing the shield doesn't break the curse. You now have a hand free, can protect your allies from missiles, and can use Deflect Missiles! You're always going to get targeted by all missiles that are near enough and it consumes an attunement slot, but hey! you're cool!
Best Answer
No, the arrow targets either the first or the second peasant in line.
The ranged attack is made only once, against the first peasant, and the target changes to either the first or the second one in line, as each target was within 10' of him. The sequence ends, since only one attack was made; the attack is not being made against the second peasant. It simply resolves against him or the first cursed peasant instead of the original target. The DM must choose between the two cursed peasants in range of the curse, in some fashion.
The 'curse' of the shield changes the target, but does not make a new attack each time the target changes. The curse says "whenever a ranged weapon attack is made against a target [change the target to you instead]." The change of target only happens on the attack, not on the targeting. Since there's only one attack, there's only one change of target.
The ability happens when a ranged weapon attack is made against a target, not when a creature becomes the target of an attack.
The Shield's effect says:
(emphasis mine)
An attack occurs when an attack roll is made. "Making an Attack" (Player's Handbook, Dungeons and Dragons 5th Edition, p. 194):
(emphasis mine)
Choosing the target is part of the attack, but only when the roll is made, does an attack occur. Once the attack roll is made, the attack is then made against the intended target, the Shield's effect then changes the target from the original target to 'you'. It's still just the one attack, so the ability only 'fires' once.