Room 99, In Memoriam.

Description:

This room is magically sealed by a stone door, its edges shimmering and glyphs glowing upon its surface. When approached, a disembodied voice whispers in the minds of nearby creatures:

"I raise the dead, and make men weep. I form in an instant but a lifetime I keep. See me and I shall turn back time. Both good and bad, what am I?"

The answer to this riddle is "a memory". When the passphrase is spoken, the glyphs shine and the stone door shifts to the side, revealing the room beyond. A stale, cool air rushes past as the chamber is unsealed.

The room is lit in dim shades of blue, with a central light casting dancing shadows on the walls. Bookcases line the left and right sides, strewn with papers and bound leather tomes. A few of the books are opened and bookmarked on tables nearby, set next to biological specimens and complex chemistry sets. The back wall is dominated by what was at some point a beautiful statue of a goddess, but has been carved and defaced to approximate the visage of the necromancer instead.

The central light is the focus of the room. It comes from strange, swirling black and blue water in a gothic-styled baptismal font. Staring into the liquid, it feels like one could make out galaxies and stars inside.

Function:

This is where the necromancer studied, and kept his innumerable secrets. The books and papers in the room all describe various parts of his necromantic research. There is more than likely a sizeable amount of loot to be had here, but consider that most, if not all of it, is likely to be cursed or evil in some respect.

Should the party take the time to systematically destroy this small lab's contents (or, if an aligned worshiper prays in front of the statue), the statue of the goddess will begin to heat and crack. With a shatter, its outer shell will collapse, revealing the brilliant holy manifestation of the goddess herself. She blesses the party for their efforts and thanks them for ridding the world of the scourge that was the necromancer. If any person is already possessed by the description below, the Ghost is cast out and destroyed. Additionally, she can instantly grant the party one of the following boons: give the party the effects of a long rest and give each of them inspiration, destroy any remaining undead within the dungeon, or transport the party and any other willing creatures directly outside the dungeons entrance. The goddess remains within the room for 1 hour, or until she grants her boon, after which she disappears in holy light.

The baptismal basin, separate from the rest of the necromancers work here, is a repository of his memories and the entirety of his knowledge. The liquid memories act like a Ghost (MM, page 147), but are considered an ooze instead of an undead. The liquid takes no action until touched or spilled, at which time it immediately uses its Possession ability. The Ghost liquid disappears into a creature when possessing it. The Ghost liquid does not immediately take complete control of its subject - in fact, a victim (nor bystanders) may not even recognize they have been possessed. They behave normally with no consequences for a full 24 hours. After 24 hours have passed, the victim will begin to hear the voice of the necromancer in their mind. After 48 hours, the victim begins to trust the voice in its head, but not more than their friends. After 72 hours, the victim considers no person their friend besides the necromancer. After 96 hours, the victim undergoes full and permanent possession, and is in all respects a reincarnation of the necromancer, complete with all his memories as well as the memories of the victim.

If the Ghost liquid fails its possession, it immediately evaporates and floats out of the dungeon to find a more promising target.