# River Styx *Generic Hazard* The "River Styx" courses through the Lower Planes. Tasting or touching its waters can shatter a creature's intellect and personality, as well as strip away its memories. Certain Fiends are immune to the river's effects. Unless immune to the river's effects, a creature that drinks from the Styx, enters the river, or starts its turn in the river makes a DC 20 Intelligence saving throw. On a failed save, the creature takes 19 (`3d12`) Psychic damage and can't cast spells or take the [Magic](Mechanics/CLI/rules/actions.md#Magic) action for 30 days. An affected creature can drink from the Styx and swim in its waters without suffering any additional effects. The effect can be ended only by the [Greater Restoration](Mechanics/CLI/spells/greater-restoration-xphb.md), [Heal](Mechanics/CLI/spells/heal-xphb.md), or [Wish](Mechanics/CLI/spells/wish-xphb.md) spell. If the effect isn't ended after 30 days, the effect becomes permanent and the creature loses all its memories. At that point, nothing short of a [Wish](Mechanics/CLI/spells/wish-xphb.md) spell or divine intervention can undo the effect. Water taken from the River Styx loses its potency after 24 hours, becoming a harmless, foul-tasting liquid. Arcanaloths, night hags, and other fell creatures might know rituals that can prolong the water's potency, at your discretion. *Source: Dungeon Master's Guide (2024) p. 78*