
Aubrey the Demented/Malformed |

Unless you get 20, you don't have a clue where the voice came from.
OK, "set up the combat" time. The room is about 80' long east-west and 40' wide north-south. The far end is actually up some stairs at a balcony level 10' up, the far end of which is rounded and the near end of which sticks out into the main room. You cannot get under the balcony - that is solid rock. In the middle of the lower section is a round pool filled with orange liquid.
In coordinate terms, the room runs from A to P west-east, and 1 to 8 north-south. The pool occupies F-G/3, E-H/4, E-H/5 and F-G/6. The stairs up to the balcony are at J-L/1 and J-L/8, running up in a west to east direction. The upper balcony level effectively occupies the following squares: M-N/1, M-O/2, L-O/3, K-P/4, K-P/5, L-O/6, M-O/7 and M-N/6.
The doors in are at A/4-5 on the western wall. At the far end, in the rounded end of the balcony level, there is another door.
The sinspawn were standing by the pool near the doors and dash to attack. I'm assuming they are attacking Hudak, since he opened the door. As yet, no one has pinpointed the position of the mystery voice. Usual drill - you al start just outside the door and can occupy the same space. Please position yourselves inside (or outside) as you see fit, providing that you don't all occupy the same square as anyone else by the end of your actions. For reference, the corridor to the doors from the room with the mutant goblin is 10' long.
Still waiting for and initiative from Lo'j/Gurney. Mystery voice goes on 15.

Aubrey the Demented/Malformed |

Initiative chart
Ugloids 18+
Larken 18
Mystery voice 15
Elisile 14
Illes 13
Hudak 11
Dravite 10+
Vethran 10-
Lo'j and Gurney 10--
Alwyn 6
Lo'j:
The sinspawn rush forward, disgusting drool running from their horrid mangled faces. One simply crashes off the Shoanti's shield, but the other manages to sink its fangs into his forearm. The damage is slight, but Hudak feels the debilitating rage begin to seep into his consciousness.
DC 12 Will save or you are Sickened. I'm assuming Hudak is in the four squares just outside the room, effectively blocking it in his enlarged state, and that the rest of the party is behind him. The sinspawn are at A4 and A5 respectively.

Elisile Starbrow |

13 on the listen check. On her first turn, Elisile will retrieve the scroll of magic weapon that Dravite purchased, and cast the spell on his ogre hook to help deal with the sinspawn.

Aubrey the Demented/Malformed |

OK, acting for Larken, he will ready an action to tumble through if a gap appears.
The strange voice shrieks, "Destroy them, spawn of the Mother! Great One, I beg you birth more of the raging ones! Gah!" it finishes, in a cry of seeming pain.
Listen check, DC 20. Lo'j can use his result from before, since it provides more info he would know already from his previous roll. The rest can reroll, as it is speaking again and therefore giving more clue of its whereabouts:
Spot check, DC 10:
Spot check, DC 20 (use the same roll as above):
Meanwhile, Elisile takes out her scroll and casts a spell upon Dravite's savage hook. Magic Weapon.
Now Illes.

Illes Elandru |

Torch in one hand, rapier in the other Illes crowds in behind Hudak ready to rush into battle as soon as the giant smashes these ancient abominations. He confidently sings a war ballad while watching for an opportunity.
Hear the sound of swords fulfill the night
Feel the winds of death on your skin
See the arrows fly, flaming in the sky
Hear the screams of men, as they die...
When he hears the voice above the fountain, the bard points it out with his sword while he continues to sing.
Swift Action: Cast Inspirational Boost (Adds 1 to my bardic music effects)
SA: Inspire Courage +2 ATT/DAM, +2 vs charm/fear (morale)
MA: Redacted.
EDIT: Having sketched out the map I realized it wasn't possible for me to move in without taking AoO or tumbling. I'm not confident enough in my tumbling yet to hit that 25 DC and if I failed that would somehow leave me inside Hudak's squares. So I removed the move part of my action.

Hudak |

Spot 19
Listen 1
Hudak hears nothing but the spraying of arterial blood(?) and gurgling yelps of dieing redhanded sinspawn.
He would bleat a Shoanti victory cry now, but for the need for the others to hear well. He is learning, the times for ebullience, and from Larkin, the times for quiet knifing in the flickering moonlight.
"Brothers," he murmers, "and sister,...that cauldron froths and boils like a witches brew."

Dravite Schorl |

Dravite steps into the room past Hudak's massive frame and prepares himself to attack anything that should attack him. "It be o'er de pool aboot 10' up....." Dravite describes what square the voice is coming from so the rest of the party can attempt to fire at the location and hit whatever it is...
Dravite moves to C5, free action:talking to describe the invis's location, readied action: attack anything that attacks me(invisible) or comes in my range(if visible).

Aubrey the Demented/Malformed |

Dravite steps into the room past Hudak's massive frame and prepares himself to attack anything that should attack him. "It be o'er de pool aboot 10' up....." Dravite describes what square the voice is coming from so the rest of the party can attempt to fire at the location and hit whatever it is...
Dravite moves to C5, free action:talking to describe the invis's location, readied action: attack anything that attacks me(invisible) or comes in my range(if visible).
The pool is big, so that only allows someone to select a square and randomly fire at it unless they made their Spot/Listen check. If they select the right square, there is still a 50% miss chance.

Larken |

Larken moves into the room, stepping past the still-twitching monster on the floor, leaving the beheadings to people with bigger blades, and moves off to one side, listening for the disembodied voice.
Standard move to E2, ready an action to throw a dagger if the voice speaks again and I can get a pin-point on it.

Illes Elandru |

Illes continues his battle song as he slips past Hudak's towering form. Inside the room now and much closer, the bard uses his rapier to point out the hidden voice.
We won this battle with might and fearless hearts
We came and we fulfilled our prophecy
So now we shall march back towards our kingdom
With heads up high and glimmering eyes
we returned with our glory
SA: Continue Inspire Courage +2 ATT/DAM, +2 vs charm/fear (morale)
MA: Get to C3
Spellcraft: 12+7 = 19, (But I can't warn anyone while continuing bardic music.)
I failed the listen check this time, but had made it with a natural 20 last round. If the voice hasn't moved I'm pointing right at it. Maybe that will help those who haven't been able to pinpoint it yet.

Aubrey the Demented/Malformed |

what square is he pointing at, can I ask?
No, you can't - he is singing and can't say, and he is ultimately pointing a line rather than at a specific point (there is no way to triangulate, and I defy anyone to do that even it they had the two pointers available in the heat of combat). So a +2 circumstance bonus is all you get - and pretty generous, given the circumstances.
That said, it is pretty obvious he is pointing, and Elisile fired at, a point above the pool. If you fail your Listen check, you can choose a square, select a height, and fire randomly. You never know, you might get lucky.