The Mountain Hammer

By The Colonel

Keywords

(Not actually randomly generated)

The Adventure Seed

The Skinny:
PCs are hired to deal with a BBEG wizard, probably a lich who has somehow laid hands on an ancient weapon called The Mountain Hammer - allegedly capable of levelling whole cities. To do so they must enter his huge mountain dungeon and … etc.

But:
A little information gathering - say, by divination magic will reveal:

• the BBEG actually took control of the weapon nearly a century ago and has not yet used it.
• He has only recently returned to the dungeon in which it is kept.
• The delay is because the weapon was getting ready to be used.
• The weapon cannot be removed from the mountain.

What's actually happening:
"The Mountain Hammer" is a potent tectonic weapon created by the magic/technology of a precursor civilisation, possibly as a civil engineering device. The BBEG located the complex in which the device is housed (indeed, large parts of which are the device¹) and eventually managed to punch a path through the automated security systems to the control centre, where he spent several years working out how to operate the device, only to discover that the geothermal energy supply that it relied upon had become radically ineffective over the years due to continental drift² and that it would take nearly a century to power up for a shot.
Being undead, he decided it was worth the wait, sealed the place up behind him and went away, leaving the system charging - he has now returned and is picking a target … it is only a few weeks before the charge buffer is full, after which he will be able to generate massive earthquakes, volcanos and similar troubles at a point of his choosing anywhere on the planet. And then wait another century before he can do it again.

So the adventure actually is:
The PCs must either find the entrance the lich used and fight their way past his followers, or a new one, overcoming the security constructs left behind by the ancients. They then have the ability to access the control centre and fight the lich himself. They are then left with a single, extremely powerful round … and a targeting system that may take them years to figure out, even with the lich's notes (better not pull the trigger by accident)³. It is possible that, once charged, the system's ancient power core may overload if not fired at something.
Otherwise the PCs have to referee who gets control of the thing (or how they shut it down permanently). They also have a huge complex full of precursor tech … and bric-a-brac … to explore.

Turning up the fun:

• As an added wrinkle - the BBEG may no longer have any quarrel with the PCs patron ("Who sent you? Really? Why? I'd forgotten about that...") and may turn out to be targeting their patron's enemy… do they still want to intervene?
• The Mountain Hammer could be tied into various historical campaign events - such as the sinking of cities like Atlantis or Ys, the Minoan eruption, Vesuvius' destruction of Pompeii, Krakatoa and other epic geological events. Equally it could be behind the creation of an island like Surtsey
• The targeting maps may be as adrift as the geothermal spike … unless there's some kind of survey satellite up there updating them, you could be shooting at a point hundreds of miles from where you think you are.
• Again, without map updates, those cryptic symbols may indicate nothing more than some potentially lucrative precursor ruins.

Footnotes

1. "Where is The Mountain Hammer?" "You are inside it"

2. "The earth-fire stones no longer serve as they did" "Why not?" "The world has moved on".

3. A large part of it consists of a huge "horizontal mirror" which is, when switched on, a holographic map table - figuring out that the coloured patterns are actually a map should be challenging for most medieval people, relating that map to known geography at least as much … even working out the cryptic map symbols should be tricky.