Lost Mine of Phandelver
A Devastation Orb is an elemental bomb that can be created at the site of an elemental node by performing a ritual with an elemental weapon. The type of orb created depends on the node used. For example, an air node creates a Devastation Orb of Air. The ritual takes 1 hour to complete and requires 2,000 gp worth of special componets, which are consumed.
A Devastation Orb measures 12 inches in diameter, weighs 10 lbs, and has a solid outer shell. The orb detonates 1d100 hours after its creation, releasing the elemental energy it contains. The orb gives no outward sign of how much time remains before it will detonate. Spells such as Identify and Divination can be used to ascertain when the orb will explode. An orb has AC 10, 15 HP, and immunity to poison and psychic damage. Reducing it to 0 HP causes it to explode instantly.
A special container can be crafted to contain a Devastation Orb and prevent it from detonating. The container must be inscribed with symbols of the orb’s opposing element. For example, a case inscribed with Earth symbols can be used to contain a Devastation Orb of Air and keep it from detonating. While in the container, the orb thrums. If it is removed from the container after the time when it was supposed to detonate, it explodes 1d6 rounds later, unless it is returned to the container.
Regardless of the type of orb, its effect is contained within a sphere with a 1 mile radius. The orb is the sphere’s point of origin. The orb is destroyed after 1 use.
Air Orb. When this orb detonates, it creates a powerful windstorm that lasts for 1 hour. Whenever a creature ends its turn exposed to the wind, the creature must succeed on a DC 18 CON saving throw or take 1d4 bludgeoning damage, as the wind and debris batter it. The wind si strong enough to uproot weak trees and destroy light structures after at least 10 minutes of exposure. Otherwise, the rules for strong wind apply (as detailed on p. 110 DMG).
Earth Orb. When this orb detonates, it subjects the area to the effects of the Earthquake spell for 1 minute (spell save DC 18). For the purpose of the spell’s effects, the spell is cast on the turn that the orb explodes.
Fire Orb. When this orb detonates, it creates a dry heat wave that lasts for 24 hours. Within the area of effect, the rules for extreme heat apply (as detailed on p. 110 DMG). At the end of each hour, there is a 10% chance that the heat wave starts a wildfire in a random location within the area of effect. The wildfire covers a 10 ft square area initially but expands to fill another 10 ft square each round until the fire is extinguished or burns itself out. A creature that comes within 10 ft of a wildfire for the first time on a turn or starts its turn there takes 3d6 fire damage.
Water Orb. When this orb detonates, it creates a torrential rainstorm that lasts for 24 hours. Within the area of effect, the rules for heavy precipitation apply (as detailed on p. 110 DMG). If there is a substantial body of water in the area, if floods after 2d10 hours of heavy rain, rising 10 ft above its banks and inundating the surrounding area. The flood advances at a rate of 100 ft per round, moving away from the body of water where it began until it reaches the edge of the area of effect; at that point, the water flows downhill (and possibly recedes back to its origin). Light structures collapse and wash away. Any large or smaller creature caught in the flood’s path is swept away. The flooding destroys crops and might trigger mudslides, depending on the terrain.