Today, a very special post, after the background of the Gnomish subraces in Mystara and the actual rules for D&D 5e, we need to cope with new ideas, we need to tinker (*Hint Hint*) and to create something new using something old, we well speak of …



BIG DISCLAIMER: the basic rules that we tried to follow where in PC2 – Top Ballista, an amazing product! We saw very quickly that there were two ways, to stay true to D&D 5e rules or to stay true to Mystara: in this post we decided for the second way so the home rules there are not completely compatible with D&D 5e but, we feel, are nearer to the Mystara setting. Nevertheless we will present a much simpler (if a bit simplistic) and completely D&D 5e compatible system for Mystara technology in the next post, discussing about its stronger and weaker points too. We will refer, though, to many concepts of this post too, so please continue to read, whatever your feeling about it!

Four of the five sub-races of gnomes are totally dedicated to science and technology, be it for survival, general progress, conquest or knowledge and discovery by itself. But how does it work?

In the Player’s Handbook (PH) 5e, it is only a side feature, Tinker, which lets you to create a very very limited number of simple inventions using a Tinker box: a lighter, a clockwork toy and a carillon.

This is very far from a satisfactory ability for a gnome of Mystara [1] and of other settings too! Not only it is not that useful, it is not even good to play a gnome with such a meager background.

We will try to expand these rules, according to two old D&D official accessories: PC2 – Top Ballista (TB) of Carl Sargent (especially pag. 34-39) and AC11 – The Book of Wondrous Inventions (BWI) of Bruce Heard. As for terminology: in TB the art of inventing is split into two independent moments, the design and the actual building. For the first you need a Meddling Box, a fundamental drawing and planning tool, and the Fantasy Physics skill (few people a part for gnomes can learn it). The building is done using custom gnome-made tools, the Skyhook Set, and using a, gnome-only, skill: Machine Building. We will, then, consider the feature Tinker as the union of Fantasy Physics and Machine Building, while the gnomish Tinker Box contains both the Meddling Box and the Skyhook Set. As for the rules follow us in the next pages!

Note: though we like the old D&D products, there are some contradictions among them and we have to follow our own judgment and taste. After TB and BWI, other products coped with flying ships, especially the Princess Ark material. We like it a lot but, from the point of view of the rules, they presented as similar the construction of magical flying ships (the Princess Ark for instance, but also the ships produced by Nithians, Alphatians, Heldannic Knights and so on) and technological ones (from gnomes and very few others; also technomagical ones are almost always of gnomish origin, like the Top Ballista aircrafts). We may in principle agree, but the consequence was the substitution of the gnome-only Machine Building skill, with a more general Fantasy Engineering and the end of the gnomish technological supremacy! We would have preferred if they had expanded the rules in the Glantri Gazetteer (Gaz3) to create big magical objects, like flying ships, instead to expand the Top Ballista rules. In this adaptation, then, we consider quite different the two kind of ships and the gnomes the only “lords” of machinery. The reason of a medieval world with magic and a slow technological advancement is due, in our opinion, to the higher interest of all the more intelligent minds to magic, instead of technology. It is easier to think, for us, to a fully magical plant to produce flying ships (e.g. in Alphatia), instead of a pseudo-technological one, a part in the case of the gnomes, off course!

So we follow the points in TB (pg. 34-39), for the entire process, but without spoilers: we want to do the conversion but not to avoid the need to have these excellent manuals! If you do not find the paper ones (good luck!) there are places selling the PDFs out there.


The first points 1-3 (Stage 1: What is the Machine For?; Stage 2: Planning the Design; Stage 3: Determining Whether it Works) do not require adaptations. You should anyway consider to check the energy sources in TB and BWI  (pag. 89) and BWI (especially at the end of the book) for ideas about inventions.

If the energy source is small, it should be part of the process (e.g. a small spring-powered weapon), if it is big/complex it should be built separately, bought (e.g. see BWI, “Dorfin’s Little Shop of Horrors” section) or you should break down the building of the project in parts (see 6).

Stage 4: How Difficult is this Going to Be?

First of all, who can design inventions? All people, but it is very very difficult without the Tinker feature! Whether acquired at the start, as a racial feature (all Gnomes, but for the Forest ones; very few, lets say 5%, of Nagpas) or bought as a Feat instead of an Ability Score Improvement.

And who can buy the Tinker Feat? Practically all Nagpas who didn’t receive it for free at the start, though only some of them have the inclination for it. A few, very very few strange and quite mad Wizards or similar type people, living in a highly cultured society (e.g. Glantri): these individuals should be considered madmen, even respect to their peers. Some other individuals, educated in gnomish society, a very unlikely occurrence, but for a dwarf orphan child from time to time, some dwarfs in Rockhome or Highforge or a very bizarre Serrainian (Serraine is a gnomish flying city, with several other races, a part for gnomes; SPOILER: we converted it for D&D 5e … stay tuned).

To see if the Design of the invention is sound, you only need a simple Wisdom check against the Difficulty of the project, but before doing it, wait for Stage 5!

Difficulty of the project:

Design Complexity






1d4 days

lighter, clockwork toy, carillon (see PH)



1d4 + 2 days

Self-reloading crossbow, bumber chute



3d6 days

Cimarron 6-shooter, tank, land walker

Very Hard


5d6 days

Plane, submersible, Volospin’s Dragonfly of Doom, Gate creation machine

Nearly Impossible


30 + 7d10 days

Serraine, Earthshakers, Gnomish Relic


– Easy Inventions can be designed and built on the fly with the Tinker Box, without the need for a workshop; the others need more time, tools and materials.

– The difficulties are mere indications, 10 can be 10-14 and a very complex repeating crossbow can be a Hard thing to build. Or a bulky yet simple invention, made portable or more efficient, may be Hard or more.

– IMPORTANT NOTE: some inventions require more than 1 Test for Design and Building, for instance a Plane is Very Hard to make but a Volospin’s Dragonfly of Doom (Gaz3) is so much more difficult, that is it may require 7 Tests, while the plane “only” 3. A Didactic Speaking Machine, able to repeat a lesson of some thousand words, maybe with the possibility to change the Memory Cylinder of the lesson, may not be enormous but it is, for sure, Very Hard too.

Examples: a plane is a 25 Difficulty invention, an Earthshaker 30 (or a bit less), Serraine or a gnomish Clan Relic is, often, a full 30 and needs dozens or hundreds of tests, e.g. team work or Plot Devide only!

The Test is modified as follows:

1) WIS Bonus, obviously

2) Extenuating Circumstances

  • Tinker Proficiency Bonus, if the Designer has it; -4 otherwise
  • No Meddling Box: -2
  • Distractions: -1 to -4
  • Gnomic Backgrounds: 0 to +2 (they give a bonus to design or build, usually not both, or to some inventions, purely Mechanical, Flying Machines, …; new Backgrounds in a future post!)
  • Repetita Iuvant*: +1 to +3

* To repeat an Invention, build a very similar one, copy a project or design in team, make things easier, but this is not very good for the pride of gnomes: they always have to improve the inventions and themselves! Exceptions: very simple inventions, like the ones in PH, are nowadays completely known and are used only with the scope of learning to Tinker. All gnomes have projects for them. It is also permitted for very big and complex inventions (e.g. Serraine), needed for the community: new plane models for the Top Ballista are, often, only slightly improved, without completely change a reliable older project.

Example: a Very Difficult invention (e.g. a plane) for a lvl 20 Gnome PC, in very good conditions. Bonus: WIS: +4; Tinker: +6; Background: +2; Special bonuses (e.g. detailed project, proximity with the Clan Relic, collaborators): 0/+4 or more. It is almost impossible to have an higher than +15 bonus and the minimum Difficulty is 25, so the pc has, in the best conditions, only a 50% of a sound design at the start! And he still has to built it!

And we still have to roll the Test and we will, on Stage 5 or … maybe not!


Stage 5: Does it Work?

In fact it is the DM that rolls the Wisdom Test (with all the modifiers) and he is the only one to know, at this stage, if the project is sound! The only possibility to know would require interactions with the Clan Relic (see the Relics of the Demihumans, in a future post).

Stage 6: Building the Contraption

The test for building the Invention is an Intelligence-based Test.

The DM may decide, in fact, that the project must be split in separate sections: for instance a vehicle could require different buildings (or even designs) for the chassis, the superstructure and the magical energy generator. The construction requires the collaboration of a suitable spellcaster (lvl 6+) to cast the appropriate spells, if the invention requires magic.

If the test at Stage 5 was bad, the project is wrong and the machine will not work, but it takes the entire Machine Building time to have the possibility to find out.

While for the Design it is unlikely to work together, this is almost always the case for complex inventions, but there is always a Chief Builder in charge of the project, almost always the Designer or a spellcaster, if magic is needed that the Designer does not possess.

To build the invention: INT Test using the DC of the Design but reduced of one step (Hard (20) to Design is Medium (15) to build; in practice lowers the Difficulty by 5). Modifiers to the INT Test:

  • Machine Building skill: Proficiency Bonus (GNOME ONLY!); -6 otherwise

  • Gnomish Backgrounds: 0 to +2 (see Stage 4)

  • If the Chief Builder didn’t design the machine: -2

  • If the Designer would be able to build the machine all by himself: +1

  • Skyhook set (from the Tinker Box): 0; -4 if they are missing.

Magical Skyhook Sets +1/+4 DO exist and they give several benefits (see TB, pg. 40).

  • No gnome workers: -2

  • The machine uses magic and there are no spellcasters: -4

Note the powerful magical implications … the machine may work even if magical in nature and no one is able to cast the spells … the gnomes’ will can really affect reality!

  • If a spellcaster different from the Chief Builder casts the necessary spells: -4

  • If it is a Rush Job (see Stage 7)): -3

gnomi e tecnologia3

Stage 7: How Long Does This All Take?

Every stage of constructions takes 11-30 gnome days: a gnome working for 1 day is a gnome day, 10 gnome working for 1 day or 1 working for 10 days are equivalent to 10 gnome days.


  • There is a limit to the number of gnomes that can work together (DM choice): for instance, a small invention can be built only by 1-2 gnomes at the time

  • Rush Job: the time required is halved

  • We propose a shorter time for Easy inventions, e.g. 1d10 gnome days.

Stage 8: How Much is this Gonna Cost? and Stage 9: Why Didn’t it work? are unchanged respect to TB.

At the end of all the Stages, your invention works (if it doesn’t at Stage 9, you repeat till it works; see TB), so what about it now! You have to wait next post for a new, EPK-made, “Stage 10: How Long Will it Last?” So you will discover how durable your inventions are, see some ideas for inventions (all from the dark depths of my mind …) and even speak about invented Vehicles!


This is the third 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

Stay tuned for the next post: GNOMES AND TECHNOLOGY – Second part.

[1] See the aforementioned post about the Gnomish subraces in Mystara and the, more general, post Common Playable Races of Mystara – first part  





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