
Black Tom |

"I'm sick", the nymph roars in a strangely hoarse voice. "Can you cure me? It will take powerful magic."
She catches a glimpse of Megan, who's snuck up behind you. "You! Go away, you hellspawn! This is all your fault?"
Megan snaps: "How could it be my fault? I was born this way, remember? Maybe it is you who shouldn't have put out to every handsome barbarian who happened to pass by!"
The nymph gasps and lapses into incoherence, screaming insults indiscriminately in Sylvan and Common. It is hard to tell if they are meant for Megan or for you.
In a short while something starts moving under the nymph's skin. It looks like some sort of parasite is trying to edge its way out. Then another appears, and yet another.
Suddenly the poor shuddering creature is virtually ripped apart into a mass of writhing tentacles and gaping maws.
"Mother!" Megan screams. "This is all your fault!"
Now roll for initiative.

Black Tom |

"I'm sick", the nymph roars in a strangely hoarse voice. "Can you cure me? It will take powerful magic."
She catches a glimpse of Megan, who's snuck up behind you. "You! Go away, you hellspawn! This is all your fault?"
Megan snaps: "How could it be my fault? I was born this way, remember? Maybe it is you who shouldn't have put out to every handsome barbarian who happened to pass by!"
The nymph gasps and lapses into incoherence, screaming insults indiscriminately in Sylvan and Common. It is hard to tell if they are meant for Megan or for you.
In a short while something starts moving under the nymph's skin. It looks like some sort of parasite is trying to edge its way out. Then another appears, and yet another.
Suddenly the poor shuddering creature is virtually ripped apart into a mass of writhing tentacles and gaping maws.
"Mother!" Megan screams. "This is all your fault!"
Now roll for initiative.

Black Tom |

What is left of the nymph goes on 9 and Megan on 15 (after Valgrim), so it's quite possible that Vulcan goes first. Valgrim (and possibly Vulcan) are up, then Megan.
In case you are wondering what you are fighting:
Knowledge (planes) 17:

Valgrim Twin-Axe |

How many and how long are its tentacles? Does Valgrim believe he will provoke an AoO if he engages it?

Valgrim Twin-Axe |

Valgrim moves to Q28, drawing his greataxe as he does so. "I know not what ye are beastie, but you gots to go!"
Attack with power attack: 1d20 + 7 ⇒ (19) + 7 = 26
Damage: 1d12 + 12 ⇒ (2) + 12 = 14
HPs: 43/43
AC: 21

Black Tom |

Sorry, was out of town for a day.
Megan hisses in anger. Her eyes flash red and Valgrim's armor is starting to feel a bit uncomfortable. Will 11 negates and dwarven bonus applies.
Vulcan, Bubba and Vug Vang are up, then the monster, then Feres and Valgrim.

Vug Vang |

"Wait, Megan! Don't hurt us! This thing is no longer your mother, I f-fear," Vug pleads hopelessly. "Don't kill the poor f-forlarren, guys..."
Meanwhile, she takes out a stink bomb and catches the writhing mass of tentacles in the smelly cloud while avoiding Valgrim.
I can't access the map from work; Vug will do a 5' step if she needs to and will place the bomb on a grid intersection to affect only the weird beast.
1d20 + 7 + 1 ⇒ (4) + 7 + 1 = 12, 5 splash damage (Ref DC 15 for 1/2) + nausea (Fort DC 15 negates)

Vulcan Stormwrath |

Spinning Vulcan sees Megan casting and spits an arcan phrase himself, his hand crackling with electrical energy as he rushes toward her, delivering a shocking punch to the snarling woman's face.
Shocking Grasp touch attack1d20 + 2 ⇒ (19) + 2 = 21
3d6 ⇒ (1, 3, 2) = 6

Friar Feres |

Round One:
"One Bull's Strength, coming right up!" Feres replies to Valgrim's request.
Feres steps out of reach of the strange creature's tentacles as he prays to his Goddess and touches the dwarf's shoulder, infusing him with divine strength. The stout priest then draws his scimitar and gets ready to join the battle.
5-ft. step to square P-29. Standard action to cast Bull's Strength on Valgrim. Move action to draw scimitar.

Valgrim Twin-Axe |

"Thank you, Friar, now watch me go to work!" Valgrim screams in primal fury, summoning his inner strength, his muscles bulging and his incisors growing to the size of a small leopard. He then directs the fury at the tentacled horror!
Attack with power attack + rage + BS: 1d20 + 11 + 1 ⇒ (16) + 11 + 1 = 28
Damage: 1d12 + 18 + 1 ⇒ (9) + 18 + 1 = 28
Bite: 1d20 + 5 + 1 ⇒ (19) + 5 + 1 = 25
Damage: 1d4 + 4 + 2 + 1 ⇒ (4) + 4 + 2 + 1 = 11
Total: 39 damage
HPs: 43/43 (+8 for raging)
AC: 19

Vug Vang |

Looking at Valgrim, Vug recoils. "Ew...that monster can't taste very good. But then again, I can't know f-for sure unless I've tried it, I guess."
Turning to Vulcan, she wails, "Wait -- you're killing her!"
She fumbles in her magical pack for Filge's syringe and loads it up with a potion of Ghoul Touch.

Black Tom |

Actually, come to think of it, Ghoul Touch wouldn't work on a fey creature. Can I have a Knowledge (arcana) or Knowledge (nature) check to figure that out?
Since you've had the potion for a while, I'll just assume that you've had ample time to question Allustan about its exact properties. That would be in character, too. :)
By the way, Megan's fey nature protects her from the brunt of Vulcan's blow. She also resists Bubba's attempt to trip her.

Valgrim Twin-Axe |

Valgrim takes another swing at the tentacled horror!
Attack: 1d20 + 11 ⇒ (9) + 11 = 20
Damage: 1d12 + 18 ⇒ (10) + 18 = 28
Bite: 1d20 + 5 ⇒ (19) + 5 = 24
Damage: 1d4 + 4 + 2 ⇒ (2) + 4 + 2 = 8

Friar Feres |

Round Two:
Realizing that Valgrim is far more effective against the creature than he could be, Feres opts to spend another moment bolstering the dwarf's defenses. With a prayer to the Dawnflower Feres touches Valgrim and calls into being a shimmering, magical field around the dwarf.
Standard action to cast Shield of Faith on Valgrim - grants a +2 deflection bonus to AC.

Black Tom |

Valgrim continues to pound away at the writhing abomination that once was a beautiful nymph, while Feres calls on the Dawnflower to protect him.
Megan scratches Vulcan for another 5 points of damage. Huge tears are starting to roll down her cheeks.
Vulcan, Vug and Bubba are up.

Valgrim Twin-Axe |

To update DM, discounting DR, if the creature has, Valgrim alone has done 14 + 39 + 36 = 89 damage to creature.

Vug Vang |

Looking uneasily at the foam and ichor frothing from Valgrim's mouth, Vug pleads: "Valgrim, if you can understand me -- can you try to restrain Megan or knock her out? We can't just kill her!"
Vug throws another stink bomb next to Megan, hoping to slow her down.
1d20 + 7 + 1 ⇒ (15) + 7 + 1 = 23, see above for effect

Valgrim Twin-Axe |

Vug's comments snap Valgrim from his bloodlust, especially when he sees the tentacled creature no longer moving. He wipes the creature's blood from his mouth and stares at it, as he dispels his rage. What have you become? The dwarves of me home would not approve! Suddenly, a great wave of fatigue overwhelms Valgrim and he leans on the wall for support, confident that this companions have the nymph situation under control.
2 rage rounds used, fatigued for 4.

Friar Feres |

Round Three:
Feres calls upon the power of the Healing Flame to mend his companions' wounds while excluding the enraged Megan and the tentacled monstrosity that was her mother.
Standard action to Channel Energy (Healing) excluding Megan and the fallen chaos beast.
Channel Energy (Healing): 2d6 ⇒ (3, 6) = 9

Black Tom |

Megan stumbles backwards under the force of the magical waters.
"A blight upon you, cursed Orcus-spawn", she sputters. "You murderous villains, you..." She sinks to her knees, crying like a little girl. "Kill me now, you stinking vermin, just as you've killed my mother!"
You get 760 xp for the fight. Welcome to level 5.

Friar Feres |

Feres pauses a moment to pray to his Goddess for guidance and to invoke Her blessing. Invoke Touch of Glory on self and cast Guidance on self.
The stout priest then sheathes his scimitar and stows his shield before moving over to Megan. He tentatively touches the forlarren's shoulder as he kneels down next to her. "Megan, I am so sorry for what happened to your mother," Feres says in a comforting tone. "I assure you that we would have helped her if we could, but I'm afraid she was killed by whatever that... thing... was that tore itself out of her. Do you have any idea how this could have happened to her?" he asks.
Diplomacy check: 1d20 + 6 + 4 + 1 ⇒ (8) + 6 + 4 + 1 = 19 (expending Touch of Glory and Guidance)
EDIT: Might need a little assistance on the Diplomacy check here Bubba - you've still got the Touch of Glory Feres imbued you with before we entered the cave.

Vug Vang |

"Megan, your mother was lost before we even got here," Vug says, sniffling and wiping away a tear. "There's nothing we could have done and there's nothing you could have done. It's nobody's f-f-fault."
She takes a look at the deceased chaos beast, but her heart isn't into it to pay much attention to the fascinating corpse.

Black Tom |

Megan breaks down and cries uncontrollably, blubbering all over the good Father's armor. After a while she calms down enough to talk. "It's my fault", she whines, inconsolably. "That thing, whatever it is, it's my twin. I know that my father raped my mother, but she's always been nice to me. She would never talk about who or what my father was, but she's been carrying the curse ever since. I know how she's struggled to keep it at bay. She knew she was dying. She even a-a-asked me to get someone to kill her before she transformed. B-b-but I couldn't bring myself to it. I was hoping that there was something you could do about it and when you failed, I just snapped. I'm sorry I attacked you. You can kill me now. I don't deserve to live anyway."
"You can have her stuff, too. She would have wanted you to have it."
The stuff in question, neatly stacked in the back of the cave, consists of 580 gp worth of gems, a scroll of Delay Poison and a rust-colored Bag of Tricks.
Megan smiles through her tears. "I used to pick playmates out of that one when I was younger."

Friar Feres |

"There, there, Megan," Feres says soothingly. "You did the right thing in trying to find help for your mother. I'm truly sorry that we were unable to help her. But at least I can help you. Please, allow me to heal your wounds, by the grace of Sarenrae, the Healing Flame."
With Megan's permission, Feres offers prayers to his Goddess, channeling healing energies to mend the forlarren's wounds.
Burn Resist Energy to spontaneously cast Cure Moderate Wounds on Megan: 2d8 + 4 ⇒ (3, 7) + 4 = 14 hp healed.
Burn Summon Monster I to spontaneously cast Cure Light Wounds on Megan: 1d8 + 4 ⇒ (1) + 4 = 5 hp healed.
But what will you do now, Megan? You are welcome to travel with us if you wish.
BT: Is there a temple of Sarenrae where we're headed - either in Forecastle or Modron? If so, Feres will offer to take Megan there to live if she would like.

Valgrim Twin-Axe |

Valgrim grumbles under his breath as he sees the party coddle Megan, "Damn nymph tried to feed us to that horror! Who can understand these non-dwarves!". He then walks away into the fresh air.