[Ajax]

Question about the Finishing Move Martial Arts Technique, the relevant chunk of the rules reads as follows:

Special Complex Action
(–10 to Initiative Score, spend 1 Edge)

The character must declare that he is performing a Finishing Move combination. The character makes an attack. If the character successfully damages an opponent with the melee attack, the character can then make an immediate extra strike against the same opponent with a +2 dice pool modifier.

Here's my question, how does this interact with the Multiple Attacks Free Action?

The attacker’s dice pool is calculated with all modifiers ... and then split as evenly as possible between all attacks, and each attack is handled separately.

It is probably easier for me to say how I think it works, and ya'll can chime in to tell me where I'm wrong:

Let's assume, to keep the math simple, that Hero McCool has AGI 6 and Blades (Kenjutsu) 4/6, for a total Kenjutsu Dice Pool of 12 and there are no other modifiers in play. Hero McCool knows the Finishing Move Martial Arts Technique, he's rolled the highest Initiative, and is fighting two Goons. Everybody's got a katana, because of course they do.

Hero McCool declares his actions for the Action Phase: His Free Action will be to make a Multiple Attack splitting his 12 dice evenly, 6 for each Goon. His Complex Action will be a Finishing Move.

Question 1: Hero McCool hits Goon #1, does damage, and invokes his Finishing Move to make his immediate extra strike against Goon #1 with a +2 dice pool modifier... So how many dice does he roll for his extra strike?

 Option A: Roll 8 dice. (McCool's split Dice Pool of 6 with the +2 modifier.)
 Option B: Roll 14 dice. (McCool's Kenjutsu Dice Pool of 12 with the +2 modifier.)

In either case, Hero McCool will then continue with his Multiple Attack, hitting Goon #2 and doing damage.

Question 2:  At this point, can he invoke his Finishing Move and make an immediate extra strike against Goon #2?

 Option A: Yes. (McCool satisfies the "If the character successfully damages an opponent with the melee attack" condition of the Finishing Move, so the "then" part of the If/Then rule must go through.)
 Option B: No. (McCool already used this on Goon #1 adn you cannot double dip.)

And of course, this leads us to Question 3, which is basically just Question 1 all over again: How many dice does the immediate extra strike against Goon #2 have?

[Hobbes]

Finishing Move is a Complex Action, Splitting your Attack is a Complex Action.  Can't make two Complex Actions in the same turn.

[Ajax]

Finishing Move is a Special Complex Action, which says it closes a mêlée attack; Multiple Attacks is a Free Action. See the Core Rulebook p. 167, 184, 196, and R&G p. 120.

[Hobbes]

Sorry, you're correct, Splitting Attacks is a Free Action.  Carry on. 

[Fedifensor]

Your dice pool against that foe was set when you made the original attack.  So if you used 6 dice against Goon #1 and hit, your follow up attack would be 8 dice.  That’s how I’d run it.

[Overbyte]

Your dice pool against that foe was set when you made the original attack.  So if you used 6 dice against Goon #1 and hit, your follow up attack would be 8 dice.  That’s how I’d run it.

I agree. It is a "Multiple Attacks" action, so you are... drumroll.. making multiple attacks. If you use a complex action to make one of those attacks into Finishing Move that attack becomes a finishing move and therefore is based on that number of dice (6).

I do agree that you could make a logical argument that making a melee attack is a complex action and when you use multiple attacks this means you melee both opponents so a complex action of Finishing Move could mean you use finishing move on both opponents.

[SR5 p196] A character may use a Free Action to attack multiple targets in a single action (see Multiple Attacks, p. 196) by splitting their dice pool. This action must be combined with a Fire Weapon Action, Throw Weapon Action, Melee Attack Action, Reckless Spellcasting, or Cast Spell Action.

So clearly it can be combined with something like Reckless Spellcasting which is a modification of Cast Spell Action.

[SR5 p281] Reckless Spellcasting: You can bypass some of the preparation, but it can take a toll on your body. This action is called Reckless Spellcasting; it lets you cast a spell as a Simple Action instead of a Complex Action, but with an added +3 Drain Value. If you decide to cast two spells as Simple Actions in the same Action Phase, both receive the +3 Drain Value.

I think you could reasonably say that Finishing Move works in a similar way applying the modifiers to both attacks so 6 and then 8 dice on each.

OTOH:

[R&G p120] A finishing move is that way-cool trid final attack maneuver the hero makes to defeat the bad guy. The character must declare that he is performing a Finishing Move combination. The character makes an attack. If the character successfully damages an opponent with the melee attack, the character can then make an immediate extra strike against the same opponent with a +2 dice pool modifier. A gratuitous Free Action to taunt the opponent can also be applied, especially if the attacker is holding the target’s spine and skull in his hands at the time. This action can only be performed once per Combat Turn. Note that use of this action requires Martial Art training.

So you could also argue that "This action can only be performed once per Combat Turn." means that you can only use it on one guy. Probably comes down to what you think makes sense as a GM and perhaps what is cinematically better in the moment. However, either way you go you will only get 8 dice for your finisher.

[Kiirnodel]

I would say there are three options:

A) Multiple Attacks is not designed to be used in conjunction with Finishising Move (ergo, you can't do this at all)

B) The effects of Finishing Move apply to the whole attack, so if you manage to hit with both (or more) attacks and deal damage with any/all of them then you get to make finishers with each one. In this case, I would say the Finisher has the same dice pool as the attack that dealt damage but with the extra +2. Example: Roll 8 dice each

C) The effects of Finishing Move applies to the whole action, but can only be used once. In this case, I would say that you can wait until all of the original attacks have resolved, then decide one that dealt damage to perform the finisher on. The attack would use your base undivided dice pool +2. Example: Roll 14 dice once.

Option A is kind of lame, rule of cool says that this is an idea worth trying out, even if it doesn't have much of a chance of panning out (since the lower dice pools). As Overbyte pointed out, the action does mention only being usable once per Combat Turn, so it is definitely designed to have limitations. My gut would say that Option B is still only performing the Finishing Move action once, its effects are just applying to the multiple attacks, but GMs can obviously feel differently, in which case I would go with Option C.

[Tecumseh]

I had Finishing Move on a PC and got to use it exactly one time over 40+ sessions, so naturally I feel a deep personal connection to this issue.

As a GM, when confronted with a situation where the rules aren't well-defined and it's up to me to find a suitable resolution, I usually default to, "If I were a PC, how would I want this to work?" That approach usually identifies the best combination of fun and balance, which is a good guideline to help keep the game enjoyable for everyone.

In this case, if the initial attack damaged both opponents then I would give the PC their choice of who to apply the finishing move to:
A) one of the defenders, using the whole dice pool +2 (14 dice in this case); or,
B) both of the defenders, splitting the whole dice pool including the +2 (7 dice for each opponent).

That gives the PC some flexibility, which in my opinion is covered by the relatively high cost of the maneuver:
1) the karma to learn it;
2) the Initiative to use it;
3) the point of Edge to trigger it.

Again, in my opinion it's an expensive maneuver, and if you're fighting mooks who are going to get tagged with a split dice pool of 7 dice then they're probably not long for the world anyway. Using a generous interpretation keeps thing cinematic, speeds up gameplay, and lets the player have an extra bit of fun too.