This is about handling attacks that should (logically) injure multiple parties, so let's handle it one example as separate entities rather than as a single issue (which I did in the first draft of this post).

Berserker Bob.
Bob is a sorcerer who, as a result of his binding, is able to attack multiple opponents each round (while in a "berserker frenzy" like you'd see in a standard fantasy game). When he goes into his berzerker frenzy he takes out multiple opponents each round. How would this be handled?

Would he have a single bound (parasite?) demon with the spawn ability? This would allow "bob" to have multiple attacks (up to whatever would be reasonable given the attack type, though with dual wielded weapons it'd obviously not be more than two) during the round, but would that be a reasonable way to handle it?

Or would it be better to implement mook rules like they have in Savage Worlds where you divvy up the crowd he's attacking into one or a few groups, and then when he does damage to the group simply describe the damage as taking out an appropriate number of the members of the group?

Or is there mechanical support for an area of effect type attack, where he just does x damage to those near him?

Which leads me to my second example.
Hand Grenade Harry.
Harry is a more modern military character with a penchant for chucking hand grenades at his enemies.

What if he's lobbing them during a complex conflict? How would this type of attack fit into the mix? Would he declare what group he's attacking as normal and let who get's damaged by it be determined by the dice and how people describe their actions? The part that creates an issue for me here is that the complex conflict rules, as I understand them, will apply your victories only to a single opponent, which seems off. I can picture an instance where he gets no victories against Adam, 4 against Barbara, and 2 against Charles, would the victories he get's against each person simply be applied against them? (yes, I may well be making this more complicated in my mind than it actually is).

I've had a few "Area of Effect" style powers come up in games before.  Like, say, a fire breathing demon capable of flooding an area with flame.  I handle it in the most simply way possible.

1) A single roll for the action.
2) When/if it comes up then all targets affected have to defend against that single roll.

That's it.  Doesn't matter if it's a grenade or suppressive fire, a fire breathing dragon.  Some people have house ruled this to require an additional power similar to Ranged called Area.  I've never felt the need.

For your beserker dude I would go with Special Lethal Damage and apply as above.  As for what type of demon there's a fun decision to be made there.

Possessors work like Passers.  They can't Confer their Powers.  That means that your berserker would have to give himself over to the Possessor and let the demon drive.  This is the most thematically and appropriately interesting but is also the most dangerous.  You have to be into the whole host/demon struggle from Sorcerer's Soul and be okay with the GM making a lot of decisions for you when then demon is driving.

Otherwise, if you're going for a more "inner hunger, feed the beast" thing then sure, a Parasite that Confers the power works as well.

Jesse

I'd handle the lobbed grenade like the ground in this example: Hand Grenade Harry can roll to lob the grenade, but once a live grenade is out there it's treated as another actor in the conflict and everyone would have to make defense rolls, even Hand Grenade Harry. Depending on the narration, I think Harry would get rollover bonuses from the throw in his defense against the blast.

John wrote:
I'd handle the lobbed grenade like the ground in this example: Hand Grenade Harry can roll to lob the grenade, but once a live grenade is out there it's treated as another actor in the conflict and everyone would have to make defense rolls, even Hand Grenade Harry. Depending on the narration, I think Harry would get rollover bonuses from the throw in his defense against the blast.

Sounds a lot simpler than I was thinking (which is likely a good thing), and I like that idea for how to handle the grenade.

I didn't see Jesse's answer before I posted, and I didn't mean to contradict him in the least. I think Jesse's right about paying attention to the tempo of the conflict.

I didn't feel like the link/example you provided was contradicting his. The gist of the linked thread was "if something will effect multiple parties, and the timing of when it 'goes off' is important to the narrative, roll it like another participant in the conflict. if the timing doesn't matter and it will effect them anyway, just have the involved parties make their own roll against it" which to me seemed to fit in with Jesse's response, just adding that if timing matters then you should treat the attack as another participant.

Both seem to fit together nicely to me (though it requires that the reader get the whole "pay attention to the context of the conflict" thing with sorcerer).

I haven't been able to give it much of a test-run, but me and my friends tweaked the Ranged ability to require you to define the nature of the "range" upon creation of the ability. 'Cause we thought "Ranged = you can use it like a gun" was kinda boring. So we had things like "Ranged: whole room" or "Ranged: over long distances if Perceived" (i.e. after using the Perception ability).