Today we complete the discussion (start reading from the First part, off course) about Gnomish technology for Mystara and D&D 5e:



After building a new invention [1] we have to ask ourselves if it will stay forever, is it so strong as an iron axe, as durable as an oak table, in short …

Stage 10: How Long Will it Last?

We created this Stage ourselves, it may seems not so important but what if it takes six months to create a new machine, that only lasts a month? Technology should not dominate, off-course, this is a fantasy world, so there are several restrictions, but they should not make impossible or useless to create new inventions: it is the whole point behind being a Gnome! At least in my opinion (and of my alter ego Glimreen Lodestar).

There are no specific rules in TB a part for a few hints, like a cumulative 1% per hour of use that the machine stops working. A bit limited and predictable, in our opinion, so we try to put together something different, taking into account, use, time, maintainance and, even, materials!

These rules are more useful for PC inventions or something they can use themselves: big inventions like Earthshakers or Serraine cannot completely fail for a wrong dice roll, they have redundant systems, fail-safe devices and so on, so they should have their own specific rules.

Can a flying city break down and fall?

Can a flying city break down and fall?

A fully D&D 5e compatible system:

As we said in the previous post it is frankly impossible to have a real Mystara-feeling for inventions with a system completely based upon D&D 5e rules: the good of the system is that it is simple and there are less calculations but it doen’st let you to properly apply all the conditions affecting design and building of an invention (as presented in PC2 – Top Ballista). Nevertheless we present to you the best approximation we could think of, we hope you appreciate the extra-effort.

For all the terms we use, refer to the previous post!

All creatures could, in theory, make an invention: it is a simple design (Wisdom Check) and building part (Intelligence Check), but there are many conditions affecting the outcome, with Advantage or Disadvantage.

Tinker: we consider it a true Skill, not a simple feature (see Gnomes in PH): with it you know how to use the tinker tools (Meddling box and Skyhook set) and you can create the Easy inventions in PH and many more. Without Tinker is should be nearly impossible to invent something: only some beings can have or buy it (see previous post). Really technological beings, with computers, airships, laser and plasma guns, energy fields (Oards, Blackmooreans, aliens in Blackmoor, Mek creators, the original Blacklore Vale Elves and Emerondians, …) are out of scope, you cannot create such non-magical marvels with Tinker.

We suggest that, as before, the DM rolls the dice behind the screen or, at least, that he always rolls at least one, without telling the player if the roll is normal or with Advantage/Disadvantage, so the player do not know if 20 is a success or 1 a failure! Let’s follow the Stages in the previous post.

Stage 1-3, 5, 7, 8, 9, 10: unchanged

Stage 4: All ideas there are ok, only the roll is different. The difficulties of the Tinker (Wisdom) Check are unchanged (Easy (10), Medium (15), Hard (20), Very Hard (25), Nearly Impossible (30)) but remember to add the Proficiency bonus. The Extenuating Circumstances can give Advantage (some Gnomic Backgrounds, in a future post; Repetita Iuvant) or Disadvantage (no Meddling Box; Distractions) to the roll.

Special rule: we suggest to not use a simple “I have 1 or more Disadvantages and 1 or more Advantages, so I roll a normal check”. Evaluate the situation and if something is much more important, go for it, for instance if you have no Tinker skill, ALWAYS roll with Disadvantage, no matter what!

Stage 6: All ideas there are ok, only the roll is different. The difficulties of the Tinker (Intelligence) Check are the same ones of the Stage 4, for instance, Easy (10), Medium (15), Hard (20), Very Hard (25), Nearly Impossible (30). Many conditions for Advantage (Gnomish Backgrounds, in a future post; if the Designer would be able to build the machine all by himself; magical Skyhook Sets (very rare, they work ONLY for Gnomes) or Disadvantage (if the Chief Builder didn’t design the machine; no proper tools; no gnome workers; the machine uses magic and there are no spellcasters; if a spellcaster different from the Chief Builder casts the necessary spells).

Special rule: like in Stage 4, evaluate more than calculating Advantage/Disadvantage and decide what is important, like not having a proper spellcaster at work for a partly magical invention. Two conditions are special!

Rush job: haste is never a good premise for a good job, always rolls with Disadvantage! The rational behind it is that in the same time scale you can roll two times (Rush Job halves the require time) and it should not be a shortcut for “greedy” players.

Tinker skill: the conditions are very tight and related to the Nature of Gnomes! In practice when building a machine/invention (as opposed to design one, at Stage 4) there are 3 situations: 1) you have no Tinker skill: you CANNOT built it, period; 2) you have the Tinker skill BUT you are not a Gnome: you roll the skill check but you do not add the Proficiency bonus; 3) you have the Tinker skill AND you are a Gnome: roll the skill check with Proficiency.

So, to resume: 1) without Tinker skill you could visualize, with difficulty, an invention, but NEVER built it; 2) with Tinker skill you can design even a difficult invention but it is more difficult to built it; 3) a Gnome with Tinker skill can design and build even the most complex machines and inventions, with the proper time, equipment and materials!

The reasons for this are several: Garl Glittergold created the Gnomes like this and, even if some very special and bizarre people are able to visualize very complex inventions, only Gnomes are able to build them (you could use gnome workforce and Chief builder to achieve the scope thought, like Alphatians do both in the Known and Hollow World), so while there are many flying ships, there is only one Flying City of Serraine!

Now let’s go back to something more general and later on we refer to our own, non D&D 5e compatible method for inventions (but in many case it is applicable to both systems).

If not properly maintained, even an Eartshaker can be useless ...

Without proper maintenance an Eartshaker can be useless …

Probability of Failure (PF %):

It starts from 0%, for a new invention, grows in several ways and should be checked before using the invention, or after a certain time (e.g. every 4 hours for a vehicle). A gnome, in theory, has no way to know for sure the PF of an invention, but can estimate it through the use of Maintenance.

  • +1d4% at every use: a shot, or a certain meaningful time (4 hours for a land vehicle, 1 for an aircraft)

  • PF grows with time IF there is no Maintenance: 1% per day or more

  • Maintenance requires 1 gnome hour for a quick checkup and to reduce PF of 1%; 1 gnome day is required to halve PF but only if the invention is not used till the end of the maintenance. PF cannot go to a lower value than 5%, through Maintenance.

  • PF Check Failure: if the test of the d100 is lower or equal to PF, there is a mishap. A PF of 5% is, in fact, equivalent to a 1 on 1d20.







Jam for 1 round, than it works again; +10% PF for the stress.



Small fixing needed (e.g. broken spring); a Gnome can repair it on the field in 1d4 rounds, with Skyhook Set (INT Check = Invention Difficulty-5); +20% PF. Before the repair the invention works at half service (shot per round, speed, …) and with -2 to Tests, if possible.



Break (e.g. complete jam of a mechanical system), it takes 1 hour to change the broken piece (INT Check = Invention Difficulty-2), if you have it. Before the repair the invention works at 1/4 service (shot per round, speed, …) and with -4 to Tests, if possible.



Major break (e.g. failure of a joint in a steam generator, all is jammed, causing 2d6 heat damage nearby), changing the damaged parts takes 1+ gnome days, if you have the spare parts (INT Check = Invention Difficulty). The Maintenance halves PF; no invention use before.



The generator explodes or simile catastrophic damages, that destroy the invention, or nearly so, and/or damages the user(s). In some cases it is possible to recover parts or to save the day at the last moment with a critical Machine Building test: this avoids the total destruction and the invention suffers a Major Mishap instead.


Example. A self-reloading crossbow with 4-6 bolts on a belt can let you avoid the Weapon Property Loading (or, for a Hand Crossbow, it acquire the Simple Weapon Property). The crossbow miss, as usual, with a 1 on a d20. The PF is checked before and if this fail, only the recharge system jams.



Some can be purely Mechanical, Magical in part and so on. Alchemy can be useful for inventions too, in some cases it is possible to devise purely Alchemical inventions. If you read the previous text you found several ideas already and many more are also in TB and BWI.

  • Crossbows!!! Self reloading, repeating (2 shots per action), double crossbow, hand self-reloading crossbows (like the Cimarron six-shooter if you know it).

  • Hand auto-basher: basically a light or war hammer, bent to 90°. The handle has a crank and a button: clicking it violently activates a spring and the hammer becomes linear again. If the gnome use it as a weapon and activates it at the right time, the spring adds to the hit: a INT Check of 15, with gnome bonuses, is needed (after the PF test), if successful it gives a +2 to Hit/Damage, if not it gives a -1 to Hit/Damage. The crank reloads the weapon.

  • Mechanical Sprinkler: bringing Holy Area Damage to undeads! This gun-like invention can spray nearly one liter of Holy Water per round in a cone area. Other, more “evil” models can use touch poisons, acids, burning oil or, simply, paint.

  • Reservoir Arrows: balanced arrows and bolts with a glass reservoir behind the tip to break on impact and deliver any kind of liquid, Holy Water, poison, acid. Or without the tip with only the reservoir, full of paint, to do wonderful jokes.

  • Rusting Shortsword: a specially hardened ceramic (or, better, Glassteel; see our next post about materials) shortsword, with a control on the hilt. A kind of a heretical weapon for a Gnome, to wreak havoc upon enemy inventors and metal clad warriors! The control opens some tiny holes and when you swing the sword a very thin dust is projected in front of the gnome: a mixture of dried pieces of Rust Monster and alchemical ingredients, the dust has the same exact effect of a Rust Monster touch. Beware of the wind!

  • Anti-Corrosion Paint: some monsters are a bane for gnome inventors, none more so than the dreaded Rust Monster! The oozes, puddings and simile monsters are usually rapidly fatal to inventions too. And let’s not forget the corroding power of acids, both natural and magical alike. This paint is a kind of purely alchemical invention to be used on metallic surfaces (maybe grace to a Steam Paint Gun) and it grants a temporary resistance to corroding substances, maybe enough to flee away or to kill the monsters!

  • Adjustable Flame Dispenser: a Fire Elemental powered blowtorch.

  • Clicking and Writing Machine: a scroll using typewriter in several versions, even a magical one, able to record in writing the voice of its inventor.

  • Flying Clockwork Toys: a must for rich children in Serraine, the Mini Top Ballista Planes are the Top of the toys. Enchanted with levitate spells, they can be commanded to float in the air and a spring-powered propeller is responsible for the forward movement.

  • War-at-Home games: mini animated golem-like soldiers can be commanded to move and fight in strategical games, following precise rules or no quarter melee. A regenerator can regrow whole soldiers from dismembered bodies to guarantee 20 or so battles, before the need to recharge it. Only for impassioned strategists or rich spoiled brats!

  • Clockwork Time Indicator: well a clock, but portable too! It weights only one kilogram …

  • Anti-Grind Oil: especially blessed by Clerics of Garl Glittergold to avoid the jamming of cogs while in dangerous and very dusty environment, like the deserts. While under the effect of the Oil, dust and similar things cannot jam the machine nor raise the PF.


4There are many examples in the old manuals, especially TB (flying crafts), BWI (vehicles of several kinds) and CM4 for Earthshakers. Vehicles are difficult and long to build but can accommodate several gnomes and, sometimes, move quickly and for long distances. In many cases they can be heavily armed and transport a lot of loot, so they are definitely interesting, at least for adventuring gnomes or, at least, for DMs in need for a deus ex machina, like an Inflatable Armadillo of Reckoning (Armored Zeppelin Bomber). There are many rules in the old sources about AC, HD, Hull Points, Movement, Maneuverability, Weapons and so on. We will discuss it again in a future post for the conversion of Serraine and the Top Ballista rules for flying combat.

Some vehicles are not overwhelmingly powerful and they do not unbalance the game, some are just a good gnomish substitute to a horse.

The rules to destroy an object in D&D 5e make it too easy do destroy even a vehicle: we strongly suggest to apply them only for “common” objects like a rope or a wooden door. Give a lot of hps for heavy, big vehicles and even a good damage reduction (depending on the materials), but we will speak again of that in the Crafting Materials of the next post!

As an example, here is the medium size walker that I created for my Highforge gnome wicca a long time ago. The first version was a spring-powered machine (requiring 6 gnomes to recharge, good thing he had 6 apprentices …) but after many adventures and a few lucky encounters in the Savage Baronies, my PC could change the energy source with a much better one. I only put the basics, skipping details of mishaps and other things.


walkerThe Marvelous, Powerful (and Power-Full) Clockwork Walker:

Didn’t we tell you the gnomes like flamboyant and magniloquent Names? Ok, now you know …


  • AC: 2 (probably AC 20 in 5e)
  • HULL POINTS: 18 (I would put x3-x5 hp and a damage reduction of 5-10 depending on the attack)
  • HEIGHT: 13′
  • WEIGHT: 600 lbs
  • CARGO: 1500 CN + 1 CREW
  • MOVE: 240′ (80′) per round; 24 miles per day

A tall machine, for a gnome, a bipedal vehicle of steel and wood with a flat platform on the top and reinforced protection parapets, big enough to allocate two gnomes. The two “arms” are very different: one a bulky and rigid steel bar ending in a red and flat “hand”; the other an elongated fuming tube, easy to orient in every direction. Behind the walker a red boiler full of bubbling water covered in the outside by a strong scaly leather.

Working Principle: the magically generated flame is contained in a Red Steel boiler, covered on the outside by Crimson Dragon skin. Several Red Steel tubes bring water and steam everywhere in the machine. It contains about 100 liters and consume 1 liter per hour in normal conditions: the walker moves at normal speed till 50 liters remaining and at half speed till 25. Steam weapons and mishaps may consume water. It contains 24 hours of operating energy and analogical indicators monitor the steam pressure everywhere.


  • Regular size Hammer-Basher: this spring-powered weapon can quickly fall down and punch both vehicles and humanoids (preferably kobolds).

DAMAGE: 2d10; AREA: 3’x3′ (yes, you punch an area…); CADENCE OF FIRE: ½ (bash, crank, bash, crank …), 2 Gnomes or equivalent to recharge; PF 5%

  • Steam Gun: it uses hot water and high pressure steam of the boiler as a weapon: the hand-held gun is used by the pilot or gunner.

DAMAGE: 3d6 or half on a Saving Throw; AREA: 10/20/30 yards cone (4/8/12 yards diameter); CADENCE OF FIRE: 1; PF 5%

The water/steam cone is devastatingly hot: it causes 3d6 damage if it hits, half if it does not (minus fire protection). The cone has short/medium/long radii of 10/20/30 yards of length and the diameter of the cone at the base is 4/8/12 yards. It consumes 1/3/5 liters of water and can shoot every round, barring mishaps.

15This is the fourth in a series of interconnected posts to play Mystara Gnomes in D&D 5e, with story, background, subraces and rules. The original scope of these posts is to fill a sore gap in the major Races of Mystara and how to play them in D&D 5e: the Gnomes’ place was left desolately empty, but no more! There will be a lot of new stuff, not only for Gnomes, like rules for inventions, magical materials and so on.

Previous posts: 1) GNOMES for D&D 5e in Mystara; 2) MYSTARA’s GNOMES IN THE 5E; 3) GNOMES AND TECHNOLOGY – First part ;

Stay tuned for the next post: FANTASYTECH AND CRAFTING IN MYSTARA

[1] See our previous post and the sources there, we still use them, though much is invented today: PC2 – Top Ballista (TB) of Carl Sargent and AC11 – The Book of Wondrous Inventions (BWI) of Bruce Heard. Also see the Gnomish subraces in Mystara and the, more general, post Common Playable Races of Mystara – first part .












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