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General Doomsday Weapons?


An idea hit me as I was trying to go to sleep last night, the "Black Door", a portal to the Plane of Vacuum so big it sucks a world's atmosphere away, destroying all life on the planet. Have you thought of a spell or device that could wreck a planet? What are your Armageddon devices?

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A Decanter of Endless Water in the hands of an animated skeleton with a permanent Magic Mouth spell. At 30 gallons a round, the world will be flooded...eventually.

Girdles of Masculinity/Femininity. Back in the 70s when fears of picking up a Girdle of Giant Strength and instead gender-bending your masculine fighter ran rampant, this item was king. We'll mass produce them and use mercenary pixies to deliver them into the home of every man in the world. No man can resist a free belt. They'll put them on, and the world will be unable to reproduce, leading to extinction.

The original Wand of Orcus. Once Orcus the Demon Prince was a badass, before he modernized to 5E and got wussified, including his famous wand. His wand originally "has a 50% chance to annihilate anything it touches" (excepting demon lords and divine beings). Steal the Wand of Orcus and get to work annihilating everything in site. Heck, annihilate your way to the core of the planet or something.

If you can't afford the Wand of Orcus, the poor man can find a Sphere of Annhiliation and do the same thing.

Unleash the Cyrinishad from the Realms. This unholy artifact tome converts anyone who reads it into a Cyric worshipper (per the novels, even other gods weren't totally immune). Have everyone you can read it. Once a god is out of worshippers, they cease to exist. The world is thrown into chaos without balance and kaboom.


Rotten DM
A Decanter of Endless Water in the hands of an animated skeleton with a permanent Magic Mouth spell. At 30 gallons a round, the world will be flooded...eventually.
Wait what. I thought they change than from 3E. Here is what I wrote of 3E and updated for something in 2008.

Decanter of endless water.
Ok let see the time to fill various things with the decanter.
For an oval swimming pool the calculation is Len * width * avg depth * 5.9 to find the number gallons an oval pool holds. For a rectangle swimming pool the calculation is Len * width * avg depth * 7.5 to find the number of gallons a rectangle pool holds. I got the calculation from a swimming pool site.
A 16 by 32 foot pool with an 8.5 deep end and 3 shallow end, holds about 22,080 gals so my parents’ pool holds a lot. The decanter has the rate of 30 gallons per round = 300 a minute = 18,000 an hour = 432,000 gallons a day, and 157,680,000 gallons a year. Then it would take 1.226 hours or 74 minutes to fill the pool at my parents’ house. Dad will be happy.
For 10 by 10 by 10 room it would take 25 minutes to fill. The orc will have time to eat his pie and brush his teeth before he starts to get worried. For a 20 by 20 by 20 room it would take 3.33 hours (3 hours 20 minutes) or just enough to enjoy one of Lord of Rings before you drown.
If want to fill the Empire State building 424 * 424 * 1250 * 7.5 (this max volume not true) 3901 + days. 10 years 251 days (I could not find where the dimensions of the breaks were)
Looking at the sample dungeon in 1e and 3e DMG and fill it to depth of one foot. The sample dungeon is 577.5 squares making 5775 * 5775 * 7.5 * 1 foot deep = 250,129,687.5 gallons or 579 days. This does not take in account the depth of the various stair ways and if the water was able to enter all parts of dungeon.
My house is 1300 square feet. So 1300 * 10 (I don’t have ten foot ceilings) * 7.5 = 97,500 gal it will take 5.4166 hours or 5 hours and 25 minutes. So if I late going home for lunch my house would be over flowing from the two chimneys. Hope the cats remember to hold their breath.
The old joke about Englishman, Scotsman and Irishman with a wall around England. England is 93,000 square miles. 93,000 * 5280 * 100 (foot wall) * 7.5 (water) = 368,280,000,000 gallons = 2,335 years 225 days. So if the decanter of endless water starting filling England on the stroke of midnight in the year 2000 you would have to the year 4334 November 24. 11/24/4334.
The Earth’s total surface area is 197,000,000 square miles. 197,000,000 * 5280 * 7.5 would result in 7,801,200,000,000 gallons. 49,474 years,323 days and 8 hours.

How much water would give to town’s people besiege? A person needs one liter of water a day to replace water loss by normal activities but needs 2.5 quarts to maintain health but this includes water contain in food.(American Water Works Association 25 facts about water). It was hard to find an exact minimum of water usage per day which did not include modern appliances. I am going to go with one gallon to include bathing, cooking, or activities. So one decanter could supply the needs of any fort. If you use the one hundred gallons of water per person per day (this include modern showers, dishwasher, and washer) a larger village can live a modern life if the population is under five thousand and the orcs are at the gates. So the only major problems would be spellcasters dispelling the decanter, weather in the winter freezing the bottle up, and vandals.

A fire engine can put out up one thousand gallons of water a minute on the water cannon. To get down three hundred gallons a minute you have to go to the “Neptune” 1837 fire engine in Toledo Ohio museum.

Decanter of Endless Water: If the stopper is removed from this ordinary-looking flask and a command word spoken, an amount of fresh or salt water pours out. Separate command words determine the type as well as the volume and velocity.
“Stream” pours out 1 gallon per round.
“Fountain” produces a 5-foot-long stream at 5 gallons per round.
“Geyser” produces a 20-foot-long, 30-foot-long 1-foot-wide stream at 30 gallons per round.
The geyser effect causes considerable back pressure, requiring the holder to make a DC 12 Strength check to avoid being knocked down. The force of the geyser deals 1d4 points of damage but can only affect one target per round. The command word must be spoken to stop it.

Oh goody. New stuff from the army.
The 3,000-gallon onion tank is a highly mobile, easily transportable, manually inflatable, collapsible fabric water tank. The tank is 23 by 28 by 42 inches and weighs 130 pounds packaged. The tank is 56 by 148 by 94 inches and weighs 24,020 pounds filled with water (Figure D-1). From fm 10-52-1 appendix d.
You got your water for the day for 3,000. Call it 30 minutes setup time. Fill time is 10 minutes on geyser. A five man team can rig a support beam so two or more men can hold the geyser. But this a little too big.

In the field mess we had a few collapsible fabric drums which carried 55 gallons when full iirc
It was basically 3 six foot long poles, a metal plate with holes for the poles and chain in center. A od green canvas bag with a dust cover and one metal rim with 3 chains connecting to the center. And the center was clipped into chain above. It took 3 minutes to setup well more if did by the regs digging footing holes for the posts, and laying down peddles to keep the mud down. Call it 10 pds when empty. Fill time is about 6 minutes on stream. Under 2 on fountain. Call it 10 minutes total setup time. Break down time is less especially if empty.


Speaking of bathing you don’t shower but bathe in your pot helmet or a bucket. So call it a gallon of water each of bathing and you don’t have to bathe each night. But if you need a shower canvas bag with shower head. Call it six poles each 8 feet long. 3 for shower head, 3 for curtain.


Creator of the Elfgrinder Mech
I don't have to create my own, because nuclear bombs, if applied consistently, produce excellent results. Joking aside, you could always just smash Atropus into the planet, drop a single piece of antimatter onto the ground, or transport a little more mass from one universe to the one your story takes place in, leading to, uh... uncomfortable density.


My PCs gave found hints of a night of 1000 sun's in the ancient past.

They found an ancient site on the moon (don't ask). A mysterious water being in the Nike told them about blast crystals.

Currently exploring an area of the not Sahara. They've found Rock paintings in the area hunting that it used to be Savannah.

They also found references to an ancient city and gave a rough idea where the area it was located at.

Basically the ancients used magic nukes on the world from the moon to attempt genocide to kill all of a gods followers. The ancients aren't around though except for a pair they revived. The ancient gods aren't around either.


My PCs kept missing the hint that the Tribbles they encountered were going to cause an ecological disaster. Time went on and on and they kept ignoring signs of famine as the tribbles destroyed entire ecosystems.

They skipped forward in time about 50 years and went back to their home continent to find it a wasteland just starting to grow back from nothing. Of course, sailors had thought they were cute and taken them to other continents too.


Ravenous Bugblatter Beast of Traal
In a 3.0 campaign I ran, the campaign took a sudden left turn when they found out that a coterie of vampires they were dealing with was attempting to find an artifact orrery that could be used to extend eclipses for arbitrarily long periods of time.

The party eventually found it first, but only because the vampires had been stymied by a mirror that they did not realize was a portal because they had no reflections. Once it was out they were pursued in a desperate trek across the continent to the dwarven homeland that had prisons/asylums carved into stone with a natural anti-magic aura and other protections that they hoped would keep out the vampires.


#1 DM advice: If you don't want it to happen, don't put it into the campaign.

I would never put a real Doomsday Weapon into my campaign because at least 2 of my players are far too
curious and chaotic and would definitely set it off to see what happens. Their characters would most likely die while gleefully cackling and giggling too. (It's an interesting campaign).


In my last Eberron campaign, I had Merrix d'Cannith work together with the lord of Blades to build the Godforged, a contruct dragon powered by a sentient magic item (Xulo). His breath had the power to turn the land into a waste similar to the Mournland, at the same time sucking the "life" out of it to be stored and used later. Their plan was to make Cyre great again (sorry...) while making the rest of the world like the Mournlands. He also made a eldritch machine that could create/destroy manifest zones on nation-wide scale.

In my Spelljammer campaign, I had a solar build connected portals around the sun of Fearun, that would completely deplete the sun, and "transfer" it in the crystal sphere where the solar empire was. Their sun had been destroyed by a previous experiment. He actually succeeded. Faerun was without a sun for 16 days. Then one of the PCs became the new sun... It's a long story.

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