Spoiled potions, broken magic items, or runoff from magical workshops can pollute waterways, creating a sludge called arcane effluence. While many Low Netherese individuals recognize the effluence's peculiar violet sheen, careless High Netherese mages usually don't even know such pollution exists.
One patch of arcane effluence covers a 5-foot square, and creatures within 30 feet of it can smell its acrid, unnatural scent. A creature that comes into contact with arcane effluence takes 3 (1d6) Acid damage. The creature takes the damage again at the start of each of its turns until the effluence is scraped off (requiring an action) or destroyed.
The Dispel Magic spell or a similar effect destroys arcane effluence.