The cavern that opens up ahead looks like a settlement.
with tents and crudely built shanties lining its irregular
walls. It appears deserted except for a lone human male
kneeling w1thin a circle of burning torchstalk mushrooms
in the center of the cave and two ragged figures lurking
nea r a zurkhwood door set .nto a wall thirty feet distant.
The figure in the circle is praying over a rotting minotaur
head but stands when he sees you. He's a thin human,
and his face and arms are streaked with dry blood.
"Friends," he says, "I have heard the call and I hope
you have too. W1th my own eyes, I saw our Great Lord
Yeenoghu slaughter the minotaurs that had plagued us.
Now we are free and strong with his blessings. We feast
while we live, and thanks to our lord, we will also feast
when we are dead. If you've heard the call, come. Join my
pack and feel the strength ofYeenoghu."
The figure smiles as he speaks, revealing teeth filed to
sharp points.Filthriddens is contained within a cave roughly 100
feet long and 60 fet"t wide. The characters enter from
a natural tunnel along one of the shorter walls. with
another tunnel exiting on the opposite side. Much of
the cave is taken up with crude shanties. Most of them
stand empty. their inhabitants either exiled or dead.
Grisha (st"e appendix C) can recount the history of
Filthriddcns and how Yeenoghu saved its denizens from
the oppression of the minotaurs. He can also reYeal how
he spent years as a slave of the drow. Grisha seeks new
djsciples to grow his cult's power.
Twelve c ultis ts (a mix of shield dwarves. halflings.
and humans) support Grisha if a fight breaks out. Ten of
them are hiddt>n in the shanties. Two more stand next
to a zurkhwood door. beyond which lies a small side
cave where cultists who have died and risen as undead
are kept If battle erupts, the cultists open the door and
release six ghouls. The ghouls ignore the cultists as
long as there a re other creatures to feed on.
MARCH TO NOWHERE
The Labyrinth is aptly named. for even the most resolute
of explorers can become lost in its depths. as a number
of modrons discovered to their dismay. Separated long
ago from their fellows during the Great Mod ron March.
these mod ron!> have been wandering the Underdark for a
longtime.
As the party travt"ls deept"r into the Labyrinth. any
character with a passive Wisdom (Perceptjon) score of
15 or higher hears the sounds of marching feet off in
the distance. To investigate the source of the noise. the
characters must travel for 15 minutes through cramped
tunnels requiring as much climbing as crawling. At the
end of this time. the adventurers emerge onto a shelf
15 feet up the wall of a broad, straight tunnel some 20
feet high.
A curious procession of creatures marches along the
tunnel below your pos1t1on. Twelve of the creatures are
identical. Each has a round body. spindly arms and legs.
a pa1r of fluttering wings rising above its arms, and a
smgle eye staring out over a wide, smiling mouth. At
the column's head stands a creature that looks like an
inverted pyramid held up by six legs. It scuttles like a
crab. On each side of its body, an eye IS set above a
mouth. Under the mouth, a single arm gnps a spear in
its hand.Twelve monodrones and a tridrone have been
wandering the Labyrinth since the last Great Mod ron
Marc h. The modrons became separated from their
fellows and trapped herr. Unablt" to find their way back
to Mechanus, the modrons have been pressing on (and
on), knowing that they must find their way back or be
destroyed in the process.
The extended march has taxed the modrons to their
limit. Most show signs of the frustration of being unable
to fulfill their mission. The tridrone has managed to
keep the group together. but it feels responsible for their
collective fate and thf"ir failure to return home. Even if
the characters ha\'e the ability to communicate with the
modrons. the monodrones' ability to communicate is all
but spent (see the "Roleplaying the Modrons" sidebar).
The tridrone can be very communicative- provided
the charactt"rs have a way to speak with it and can allay
its suspicions. A character can persuade the tridrone
of the party's good intentions with a successful DC 15
Charisma (Persuasion) check. They have advantage on
the check if the party indudes one or more modrons.
Once convinced of the characters' friendly intentions.
the tridrone tells them that it and its fellows are on
a mission of supreme importance. though it doesn't
reveal the nature of that mission. A character can puzzle
out th e reason why th r modrons might be here by
making a DC 20 Intelligence (Arcana) check. Success
indicates that the chamctcr recalls stories about the
Great Modron March, which occurs every 289 years
and sees a vast army of modrons marching across the
Outer Planes. If the check succeeds by 5 or more. the
character also knows the last march happened over twoROLEPLAYING THE MODRONS
Modrons have no sense of individuality. They are a
collective and refer to themselves as "we" or "us." As a
result, modrons don't understand individuality 1n others.
When speak1ng to a group. the tridrone might focus its
attention on the adventurer 1t beheves to be at the top of
the party's h1erarchy even while talk1ng to another.
Monodrones can normally relay messages up to forty·
eight words long. However, years of wandering have
degraded these creatures so that they can speak only a few
words or phrases before sputtenng off mto clicking and
popping noises. Among the words the monodrones repeat
are "march," "Mechanus," "seventeen" (the number
of cycles of the plane of Mechanus that mark the Great
Modron March), and "lost."Cll \PTl'R I~ I THE LARYRI:-<TH