Ayanna, Glinsael, and whoever else comes along (Snet tries once more to warn you away from the hallway, but gives up and goes back to his 'babies') goes down the hallway and stands at the doorway to the antechamber.
Once again the air feels heavy and pregnant with menace. There's a chill deeper and sharper than the rest of the basement.
Three or four steps into the antechamber and the temperature plummets. A horrible frigid cold fills the room and within moments everyone skin and hair and clothing are covered in a rime of frost.
Two or three more steps and a figure appears in the doorway to the room beyond. An apparition. It appears human. Female. Middle aged. The face has the delicate cheekbones and long chin that bespeaks a noble heritage. It wears a finely made (but not at all large or ornamental or impractical) dress (not quite a gown, but Glinsael figures she guess that word well enough).
She holds a knife in one hand. Her face and chest have large gouges in them like wounds from a large, heavy blade. The wounds are the same as show on the corpse on the floor.
Her face is contorted with rage. Anger and fear roll out from her like waves on a beach.
She shines with a cold, cold blue-white light. But it does not illuminate the shadows around her.
OUT!
The word is suddenly, shockingly, painfully hissed directly into the minds of all present.
The apparition does not move.
OOC:
1. Everyone please made a DC10 Constitution save or take 1 level of exhaustion. Anyone resistant to cold damage automatically passes. Anyone with experience in high altitude or cold climates can roll with Advantage.
2.
Spoiler for DC12 Arcana check, anyone with experience with undead or the Planes may roll with Advantage: (Highlight or hover over the text to view)
The particular way she manifests, and the darkness around her, indicates her undead state is influenced by (or perhaps even caused by) strong influence from the Shadowfell.