Devastation Orb of Water
Wondrous Item, very rare
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 components, which are consumed.
A devastation orb measures 12 inches in diameter, weighs 10 pounds, 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 hit points, and immunity to poison and psychic damage. Reducing it to 0 hit points 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 one use.
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 in chapter 5 of the Dungeon Master’s Guide. If there is a substantial body of water in the area, it floods after 2d10 hours of heavy rain, rising 10 feet above its banks and inundating the surrounding area. The flood advances at a rate of 100 feet 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.
Source: Princes of the Apocalypse p. 222