Unless immune to the river's effects, a creature that
drinks from the Styx or e nters the river is targeted by a
feeblemind spell (save DC 20). A creature must repeat
the saving throw whe never it starts its turn in the river,
until it fails the save. A feebleminded creature can drink
from the Styx and swim in its waters without suffering
any additional deleterious effects.
If a c reature fails its saving throw a nd remains unde r
the spell's effect for 30 consecutive days, the effect be-
comes permanent (no save) and the creature loses all its
memories, becoming a near-mindless shell of its former
self. At that point, nothing s hort of a wish spell or divine
intervention can undo the effect.
Water take n from the River Styx loses its potency af-
ter 24 hours, becoming a ha rmless, foul-tasting liquid.
However, arcanaloths, night hags, and other fell crea-
tures might know rituals that can prolong the wate r's
potency, at your discretion.
ALTERATIONS TO MAGIC
Avernus is the entrance to the Nine Hells, a battlefield
drenched in eldritch energy. The magic of the Weave
works diffe rently here, manifesting in unusual ways.
COSMETIC SPELL MODIFICATIONS
At your discretion, a spell can be modified cosmetically
to enhance the corrupting nature of Avernus. Here are
some examples:
Bigby's Hand. T he conjured hand is a fie ndish claw.
Find Familiar. The familiar i s an imp.
Find Steed. The steed is a nightmare.
Find the Path. An imp appears and begrudgingly guides
the caste r to the desired location while compJajning
the whole time, disappearing when the destination is
reached or the spell e nds.
Fog Cloud. Moaning faces appear and fade in the yellow
fog that smells like s ulfur.
H ellish Rebuke. The cackling of imps accompanies the
fire unleashed by this spell.
Mage Hand. The summoned hand is shaped like a claw.
Rary's Telepathic Bond. Characters linked together by
the spell can hear vague, infernal whispering in the
background, but can't make out what's being said.
TELEPATHIC COMMUNICATIONS
Archdevils can eavesdrop on communication spells
s uc h as message and sending sent from or within the
Nine Hells. Because of this, those engaging in telepathic
communication a lways have the feeling that t hey are
being listened in on or watched by some infernal pres-
e nce, even if an a rc hdevil isn't eavesdropping on their
communication.
Telepathic communications via magic items such as
sending stones or a helm of telepathy can be overheard
by an a rchdevil as well. Communicating with a serpen-
tine owl, an orb of dragon kind, or a sentient weapon
also runs the ris k of being overheard in Avernus. Rings
of mind shielding work the same in Avernus as they
do on any other plane and are highly valuable items in
the Nine Hells, coveted by all fiends to avoid the prying
minds of their masters.