On conducting a metaconcert

[Venger]

How does metaconcert (http://www.d20srd.org/srd/psionic/powers/metaconcert.htm) work?

I tried searching the "metaconcert in the playground" thread, but did not really get any answers.

Could someone explain how a typical use of metaconcert would go?

[Psyren]

I'll assume you're asking about the 3.5 version (because the PF version is much clearer, albeit possibly nerfed.)

The simple answer is just to use the PF version, (http://www.d20pfsrd.com/psionics-unleashed/psionic-powers/m/metaconcert) which is much easier to follow. Using the 3.5 version will cause an inordinate amount of headaches. But if you want to try, I'll outline as much as we know and provide suggestions on the gaps and stuff that doesn't make sense. Here goes:

1) You spend 10 rounds manifesting.

2) At the end of this time, you choose up to 9 psionic allies within 20ft. of you, and then choose a number. Each participant donates that many of their power points into a collective pool.
(Ambiguity 1: it is not clear what happens if any one member has insufficent points to donate to the pool, or even no points at all in the case of creatures who are only psionic due to PLAs. Psyren suggestion: if you designate a number that exceeds any member's current PP, that member simply donates whatever they have and joins anyway.)

3) The party reaches consensus on who the conductor will be.
(Ambiguity 2: what happens if there is a disagreement, and how long does it take to resolve? Psyren suggestion: due to the metaphysical nature of the network being formed, the group is able to choose a conductor at relativistic speeds, thus no actual time passes.)

4) An "entity" is created that manifests powers using the powers in the collective pool formed in step 2. It knows every power that the participants know.
(Ambiguity 3: What is the entity's ML? Psyren suggestion: Give it the ML of the highest-ML participant in the concert.)
(Ambiguity 4: Can the entity be targeted or attacked? Aside:This is going to be the biggest source of cranial trauma this power can give you. Basically the power creates... something... that manifests on the group's behalf and at the conductor's direction. It gets its own set of actions (no more than one person would get - i.e. move, swift, standard, immediate, that jazz) and it has to make saving throws, but nothing else about it is known - no hit points, no attributes, whether it's visible, tangible, detectable by any means (save by the power's own display), what could possibly happen to it if a save is failed, nothing. Psyren suggestion: I would treat it like a vestige manifestation - just totally unaffected by most things. Roll saves for it, sure, but unless the effect does something like drain power points or force concentration checks it's probably not going to do anything to the entity. So to summarize: stuff that hurts it probably won't do anything, stuff that takes its actions away or otherwise keeps it from manifesting will.

5) The group must stay within 20ft. of one another or they drop out/the power ends (if it's the conductor that gets out of range.) They can move together at a speed of 10ft.
(Ambiguity 5: How does the group move? Psyren suggestion: Have everyone ready a move action if they want to go anywhere. Yes, I know readying is normally a standard action; roll with it. Ugh, this thing is so badly written.)

6) If you leave the concert (early, or when it ends) you get a number of PP back equal to the total left in the pool divided by the number of remaining members. Any leftovers go to the conductor.
(Ambiguity 6: Is it possible to exit a metaconcert with more PP than you donated to it? Psyren suggestion: Yes, you'll make your life a lot easier if you just do the division straight rather than tracking who donated how much. But, see below.)
(Ambiguity 7: What if that number is higher than your maximum PP? For example, you're a psionic creature who doesn't have a PP reserve, or you're a Soulknife whose max is 2 from Wild Talent? Psyren suggestion: You shouldn't reclaim more than your maximum, especially since it's unclear where that PP goes if you don't spend it. So if you do the division and the amount the person gets is more than their maximum (including creatures with no pool at all, i.e. maximum of zero), then put any excess back into the pool. If the entire power has ended, divide that amount among everyone else too.

I hope this long-winded houserule-laden mess helps.