Lands of Erdos
Wondrous item, legendary
This 5-feet-radius metal sphere is the most terrible weapon ever developed.
A creature can use an action to trigger the detonation timer. The creature can set the timer to up to an hour. Once the timer reaches zero, the device detonates. A creature may attempt a DC 18 Intelligence (Arcana) check to deactivate the device if it is primed. Failure by five or more detonates the device prematurely.
The detonation is the instantaneous creation of a massive disintegration field engulfing a 5-mile radius sphere. Anything outside this field is unaffected by the disintegration, even if standing mere inches away from the effect’s edge.
Everything within the field however, must make a DC 20 Constitution saving throw (objects automatically fail the save). A target takes 60d6 + 100 force damage on a failed save, or half as much damage on a successful one. Neither immunity nor resistance to force damage can reduce this effect. Anything reduced to 0 hp from this damage (including magic items, but not artifacts) is disintegrated.
The energy immediately destroys all magical barriers and effects with no exception, including those created by spells such as prismatic wall or force cage. It otherwise functions as a dispel magic spell, cast using a 9th-level slot. The dispel magic effect also affects everything in a 5-mile radius outside the disintegration field.
The blast itself is a brilliant flash of light. Anyone looking directly at the blast, must make a DC 15 Dexterity saving throw. Those that succeed avert their eyes in time. Those that fail are blinded for one minute. A creature blinded by this effect may make a DC 15 Constitution saving throw at the end of each its turns to end this blindness.
The dust released by the disintegration effect creates a massive mushroom cloud if detonated near the ground and may affect visibility.
Over the next 2d10 days, there is a 30% chance that a magis cloud will form, creating a hazard in the area that can last for years. Other magical phenomena may also take place at the DM’s judgement.