Dungeon Master's Guide 5E

Stygia is also home to its previous ruler, the
serpentine archdevil Geryon, who was dismissed
by Asmodeus to allow the imprisoned Levistus
to regain his rule. Geryon's fall from grace has
spurred much debate within the infernal courts. No
one is certain whether Asmodeus had some secret
ca use to dismiss the archdevil or whether he is testing
Geryon's allegiance for some greater purpose.
Malbolge. Malbolge, the sixth layer, has outlasted
many rulers, among them Malagard the Hag Countess
a nd the archdevil Moloch. Malagard fell out of favor and
was struck down by Asmodeus in a fit of pique, while
her predecessor, Moloch, still lingers somewhere on
the sixth layer as an imp, plotting to regain Asmodeus's
favor. Malbolge is a seemingly endless slope, like the
sides of an impossibly huge mountain. Parts of the
layer break off from time to time, creating deadly and
deafening avalanches of stone. The inhabitants of
.Malbolge live in crumbling fortresses and great caves
ca rved into the mountainside.
Malbolge's current archduchess is Asmodeus's
daughter, Glasya. She resembles a succubus with
her small horns, leathery wings, and forked tail. She
in herited her cruelty and love of dark schemes from
her father. The citadel that serves as her domicile on
the slopes of Malbolge is supporte d by cracked pillars
a nd buttresses that are sturdy yet seem on the verge of
collapse. Beneath the palace is a labyrinth lined with
cells and torture chambers, where Glasya confines and
torments those who displease her.
Maladomini. The seventh layer, Maladomini, is ruin-
covered wasteland. Dead cities form a desolate urban
landscape, and between them lie empty quarries,
crumbling roads, slag heaps, the hollow shells of
empty fortresses, and swarms of hungry flies.
The Archduke of Maladomini is Baalzebul,
the Lord of Flies. A bloate d fiend with the lower
body of an enormous slug, Baalzebul's form was
in flicted on him by Asmodeus as punishment for
wavering loyalty. Baalzebul is a miserable and
degenerate monstrosity who has long conspired to
usurp Asmodeus, yet has failed at every turn. He carries
a curse that causes any deal made with him to lead to
ca lamity. Asmodeus occasionally shows Baalzebul favor
for reasons no other archduke can fathom, though some
s uspect that the Archduke of Ness us still respects the
worthiness of this fallen adversary.
Cania. Cania, the eighth layer of the Nine Hells, is
a n icy hellscape, whose ice storms can tear flesh from
bone. Cities embedded in the ice provide shelter for
guests and prisoners of Cania's ruler, the brilliant and
conniving archdevil Mephistopheles.
Mephistopheles dwells in the ice citadel of Mephistar,
where he plots to seize the Throne of Baator and
conquer the planes. He is Asmodeus's greatest enemy
a nd ally, and the Archduke of Ness us appears to
trust Mephistopheles's counsel when it is offered.
Mephistopheles knows he can't depose Asmodeus until
his adversary makes a grave miscalculation, and so
both wait to see what circumstances might turn them