D&D General Fantasy Equivalent of the Nuke

[Dannyalcatraz]

Harry Turtledove’s Darkness series is essentially a retelling of WW2 on an unnamed fantasy world. Most of the real world’s weaponry has some kind of fantasy version in these novels. As such, there are two magical WMDs devised and released upon the world.

The first is a specialized ritual in which the Nazi analogues’ sacrifice of the setting’s analogue to Jews and other undesirables of the 3rd Reich results in a targeted wave of necromantic energy across a wide area. Essentially, it combines the Nazis’ Final Solution with battlefield deployment of nerve gasses.

Countering this is a fantastic version of the Manhattan Project. The ritual they devise utilizes the temporal displacement of living animals which are direct ancestor/descendant pairs. The massive amounts of mystical energy derived can then be directed to various targets.

Mimicking the atomic bomb using strictly D&Disms, though?

I’d have someone figure out how to simultaneously- but briefly- open tiny portals to all of the elemental & energy planes in an inward-facing spherical array within inches of each other. Perhaps they’re housed in a sphere of force that also has a stasis effect.

When the stasis & force effects are ended, KABOOM!

 

[Ralif Redhammer]

That is a fiendish magic item! Flip of a coin whether you have a Tarrasque going through everything in its way to get you, no thanks!

I prefer the talisman of final destruction, a single-use magic item from the adventure "Sleeping Dragon," by Bill Slavicsek, (Dungeon #48) which summons the Tarrasque to you and lets you give it one order, which it carries out for 1d6+8 days, after which there's a 50% chance that it goes back into hibernation...and a 50% chance that it immediately seeks to destroy the talon's user.

Also, in Reverse Dungeon (affiliate link) there are single-person recreations of rain of colorless fire and invoked devastation, which while less powerful than the originals, can potentially be learned by a PC. Casting either deals Hit Dice of damage equal to the caster's level, over an area a number of miles in diameter equal to the caster's level...though it also kills the caster in the process.