The words recently came out of my mouth where I said all the investment of time and thought in operating the carefully structured ordering of Action Resolutions has no effect on combat outcomes, because it only sets out the order in which things get resolved within the PCs' turn.
   Actually, what it does is let committed toe-to-toe combatants go before the more circumspect shooters and movers – so they’re less likely to come up targetless and lose their turn – where the more circumspect ones are more likely to be able to redirect onto something else if need be.  Which is admittedly pretty neat in itself.

But then coincidentally, a couple of days later I saw a Bob the World Builder YouTube video singing the praises of Daggerheart for the way its side-based Initiative allowed everyone at the table to choose the order in which their actions were resolved (like he said PbtA and Nimble also do; I’m sure there are others), allowing them to meaningfully work together for a more engaged experience all round.
   It has to not just become a popularity contest, let the pushiest player dominate, or see the whole group spiral down into committee-decision paralysis.  But the possibility of allowing teamwork decision-making to plan and collaborate instead of taking it in turns to perform unilateral actions (with a covertly competitive vibe going on?) has got to be worth going for.

Cheers!
–Os.
 

I don't think I've ever seen game mechanics for (even dream-imitations of) the scabbard of Excalibur.  Sweet!  

Do you have an angle on Arthuriana in Hyperborea, @Carnby, or is this just what Kelts would like to recreate?

I agree with the replies above; Magic Missiles strike the targets the caster points at, without any ambiguity from phrases like 'intended target' or anything.

But I read into it from first principles for myself as well – in the 3E rules; not going back to 2007!
   I think it might be worth pointing out Magic Missile's "instantaneous" Duration, give or take "instantaneously" pointing at multiple targets(!).  The caster doesn't have the time to see the effect of one missile before launching the next; and the missiles aren't in flight long enough for the interweaving Mirror Images to foil them.
   I slightly wonder at the multiple images using their DX bonuses to dodge missiles, and whether missing one ought to have a chance of hitting another!  But that's not the spirit of the spell, so let's not go full 'simulationist'

Cheers,
–Os..

You could indeed call it "supine" as distinct from "prone".  But I just found this in p 271's rules for PUSH attacks, where we have "knocked down":

 A knocked-down combatant is considered
    hindered and suffers a -2 AC penalty.

Page 264 tells us hindered means -2 AC but says nothing about it causing any penalty to attacks.  

rhialto wrote:

Never encountered in all my days, but my first instinct is "a prone attacker cannot attack".[...] I'd likely levy a -2 or -4 attack roll modifier [..]

I totally have encountered this in several game systems over the years.  In systems where getting up from prone takes your whole action, every player wants to attack from prone, even at a penalty, rather than spend that round not getting to roll something.

So that means it's telling that p. 264's "Table 139: Attack Roll Modifiers" does not include any entry for Attacker is Prone.
   Surely if attacking from prone were possible it would be at a penalty.  Sure, a movie-hero could hamstring their opponent from prone, but doing so should require them to heroically overcome more than just the -1 penalty for 'defender is in a higher position'.  They have options, but fewer than a standing combatant's, and they are therefore easier to predict and to defend against, amounting to a penalty worse than that -1...

And since there's nothing listed for it, I suspect the intention was that prone characters are not supposed to be able to attack at all, but are assumed to get back to their feet before renewing the fight.  (If they weren't treated as prone only temporarily because of the attacker having had the drop on them; per p. 266's "A surprized party may be considered prone if caught completely unawares (e.g., sleeping, eating, reading).").

But if a prone creature could not attack, that would mean that Pyromancers' Fire Web spells, which keep the victim prone for multiple rounds, would be an instant, no-challenge, encounter-winner.  And we don't really want that, do we?