Kuo-Toa Tidelight Vent
This submerged Netherese pressure vent is an old city-defense engine that has been re-purposed by kuo-toa to channel elemental force through flooded streets. It lies silent until disturbed, then exhales a violent burst of superheated brine and crackling force that tears through water like a thunderclap in a sealed chamber.
Kuo-Toa Tidelight Vent
Defenses
Detection
“A bronze-and-blackstone lens set into the floor of a sunken Netherese avenue, ringed by barnacle-crusted runes and coral-grown conduit tubes. When stirred by movement, faint blue-white light flickers behind the lens like a trapped storm trying to breathe.”
Standard Engagement
A creature enters the 15-foot-radius pressure ring, disturbs the central lens, or damages a linked rune plate.
Passive until triggered. On initiative count 20 of the round it is triggered, it releases a burst of elemental pressure. After that, the area roils for 1 round and the hazard powers down unless it is triggered again before it resets.
The hazard resets in 1 minute if not disabled. If triggered repeatedly in the same hour, the damage increases by 1d10 fire and 1d10 lightning each time, to a maximum of 6d10 each, until the next long rest as the vents overheat.
Triggering the vent forces each creature in a 15-foot radius to make a DC 15 Dexterity saving throw. A creature takes 22 (4d10) fire damage and 22 (4d10) lightning damage on a failed save, or half as much damage on a success. Underwater, this damage manifests as scalding pressure, steam-shear, and electrical shock.
A creature that fails the save by 5 or more is also pushed 10 feet directly away from the vent and is knocked prone if it is on a surface or platform. In water, this means it is shoved off ledges, into rubble, or into deeper current.
The area within 10 feet of the vent becomes violently churned until the start of the hazard's next turn. That area is difficult terrain for creatures moving against the current, and ranged weapon attacks through it are made with disadvantage.
While underwater, creatures that fail the Dexterity save against the vent cannot benefit from resistance to fire damage granted by mundane immersion or standard clothing. Magical resistance works normally.
If a creature of the kuo-toa's choosing presents a living sacrifice, the kuo-toa can use an action to force the vent to trigger immediately, even if no creature has entered the area yet.
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