The Dragonlance Nexus

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Gnome Inventions

D&D 3e (3.0/3.5) Rules

by James O'Rance

New Feats | Determine DC & Device Complexity | Final Difficulty Class | Table 1: Gnome Device Complexity | Size of the Device | Cost of the Device | Building the Device | Gnome Mishaps | Example Gnomish Devices

Gnomish inventions are a form of fantasy technology, as opposed to the advanced technology found in Chapter 6 of the Dungeons & Dragons Dungeon Master's Guide. The inventions of tinker gnomes are a mixture of basic scientific principles, fantastic Renaissance devices reminiscent of Leonardo DaVinci, and mad creative genius. Gnomish inventions are almost exclusively driven by basic mechanical devices: gears, windmills, waterwheels, pulleys, and screws. Gnomes have done elementary work in chemical combustion (usually with explosive results) and can generate electrical charges of great power, but find little purpose in it. Clockwork mechanisms are a relatively modern development of gnomish technology. Only in Taladas is steam power used to any great degree.

When a gnome sets out to design some mechanism, it's a good bet that the invention will be at least 30 times larger than necessary, will make ten times as much noise as acceptable, and will have many totally redundant features (if it works at all). Only those gnomes considered "mad" by their kin are able to create devices with any degree of elegance and efficiency.

New Feats

Create Technological Device [Special]

This feat is required for a gnome character to create any device of gnomish mechanical genius, rather than the equipment found in the Player's Handbook. Gnomes without this feat typically belong to one of the purely practical or theoretical guilds, such as the Astronomical, Medical, and Philosophical Guilds.

Prerequisites: Gnome, Int 13+

Benefit: The character can design and build various technological devices. The powers of such devices, as well as their cost and the DC of their construction, are arrived at by following the Gnomish Invention guidelines. Once the device has been designed and the parts purchased, the success or failure of the invention attempt is determined by a Craft skill check. The following Craft skills are appropriate for gnomes with this feat:

Aerodynamics Chemistry Hydraulics Thermodynamics
Appliances Communications Hydrodynamics Transportation
Architecture Engineering Kinetics Weapons

Normal: Characters with the Craft skill are able to create normal or masterwork items, but not those that require technology greater than the medieval norm.

Mad Gnome [Special]

Mad gnomes never do their work properly as far as other gnomes are concerned—they lack proper "gnomish creative genius," and their inventions usually work too well! Other gnomes do their best to help them, and the Medical Guild has treated several with a variety of devices of varying effect but little success.

Prerequisites: Create Technological Device, Wis 15+

Benefit: Mad gnomes benefit from a +2 bonus to the Craft skill checks when devising gnomish inventions. If the character attempts to build a device that she has previously built successfully, she gains an additional +3 bonus to the Craft skill check when building that device.

Determine DC & Device Complexity

To create a gnomish device, you must first determine its abilities, size, and the Difficulty Class of its construction (based on the level of complexity of the device). A gnome character's player should follow these steps:

Table 1: Gnome Device Complexity shows the complexity modifiers for the various effects that gnomes commonly like to see on their devices. To determine the Difficulty Class of building the device, find the highest complexity modifier and add one point for each effect beyond the first.

The DM is the final arbiter of just which effects are needed to make a device function.

Ask all of the following questions when designing a gnomish device:

Will it inflict damage, protect a character from damage, or restrain a creature?

Refer to Table 1: Gnome Device Complexity to determine the complexity modifier from the amount of damage or the level of protection required.

If the device is designed to restrain a creature, then determine the complexity modifier by the maximum Size of creatures that it can restrain.

Does it move something or itself?

Determine if the device moves another object (e.g. throws a victim) or moves itself (e.g. a flying machine). If the device throws things, then consult the column labeled "Move Object" on Table 1. If the device moves objects within itself (e.g. a steam-ship), then check the column labeled "Speed." The numbers given in these movement columns can be either a total distance or a distance per round, whichever is most appropriate).

Does it alter the environment or have an area of effect?

The amount of material altered and whether the affected region is inside the device are an important consideration. If altering material inside the device, remember that the final size of the device will dictate how much material can be altered at once. If altering an external environment, then the size rating of the environment altered should be added to the complexity modifier (see Table 2: Size of Gnomish Devices).

Note that gnomish devices are often larger than the environments that they alter.

Does it alter an existing object?

Gnomes commonly build devices to help them build devices. If the device takes an unfinished or partially finished object and changes it into a more finished object, then the device has this effect.

Do the effects last for more than one round?

Check the Duration column for the complexity modifier, if appropriate.

Determine the complexity difference between the original object and its final state. This is done by subtracting the complexity modifier of the finished object from the complexity of the original object.

For example, a machine designed to craft raw quartz into finished lenses takes an object of complexity modifier 20 and makes it into an object of complexity modifier 1, a difference of 19. A machine that takes glass (complexity modifier 8) and makes it into finished lenses (complexity modifier 1) has a complexity modifier of 7.

Final Difficulty Class

Each effect has a complexity modifier. Often a gnome will build a device with multiple effects; for example, a machine that moves along the ground and fires flaming metallic rocks has modifiers for both speed and damage. To determine the final Difficulty Class to build a device, first find the highest complexity modifier among the effects listed. Increase this modifier by 1 for each effect beyond the one listed. In the case of the vehicle mentioned above, that is one additional effect so 1 is added to its highest complexity modifier to determine the final Difficulty Class.

Difficulty Class = highest modifier + 1 per additional modifier
Click for Table 1: Gnome Device Complexity

Size of the Device

The size of a gnomish device greatly affects the ease of its creation and determines whether sufficient materials are available to build it. Generally speaking, the larger the device, the less complicated it is (i.e. the gnome has a better chance of building it successfully), while the smaller the device, the more complicated it is (i.e. the gnome is likely to fail). This reflects the gnomish philosophy of engineering. However, larger devices require more materials to build, are more expensive, and are harder to move.

After determining the Difficulty Class of the device, the player then chooses the size (based on the descriptions on Table 2: Size of Gnomish Device). This grants the character a modifier (either a bonus or a penalty) to his Craft skill check.

Table 2: Size of Gnomish Devices
Size Example Check Mod.
1 Small Sack -9
2 Knife -8
3 Sword/Pouch -7
4 Crossbow -6
5 Backpack -5
6 Chest -4
7 Couch -3
8 Small Cabinet/Human -2
9 Large Cabinet -1
10 Large Wagon 0
11 Small Cottage +1
12 Large Cottage +2
13 Mansion +3
14 Tower (3 stories) +4
15 Tower (6 stories) +5
16 Tower (10 stories) +6
17 Small Keep +7
18 Castle +8
19 Township +9
20 Mountain +10

Cost of the Device

Each device must have a number of components equal to its Difficulty Class. If the device has a DC 15, then it must have 15 separate parts. The components used are determined by the desires of the gnome designer, with at least one part from each of the first four groups. You cannot purchase any component type more than once — purchasing Pulleys gives you all of the pulleys needed for the device, not merely a single component.

Exception: Devices with a Difficulty Class higher than 20 are so horribly complex that you may purchase multiple clockwork components.

Parts from Group #5 are required for any device that has a delayed action, an automatic sequence, or has anything to do with information storage or communication.

Multiply the total costs of all components by the size of the device to determine the cost of building the device. Gnomes often think up items that are far too expensive to build!

It must be noted that a gnome can construct any of these items from elementary materials (cut wood from trees for frames, cut gears from sheets of metal, etc.), but this doubles the construction time of the device.

Table 3-A: Device Components and Their Costs
Part Group #1: Mechanical Transmissions
Pulleys 5 stl
Shafts 10 stl
Gears 20 stl
Belts 100 stl
Screws 500 stl
Blades 1,000 stl
Part Group #2: Other Transmissions
Fins (Vanes) 10 stl
Rods (Steel) 20 stl
Glass Rods and Panes 40 stl
Bellows 200 stl
Pumps 1,000 stl
Tuning Forks 2,000 stl
Part Group #3: Drive Sources
Counterweights 30 stl
Coiled/ Wound Springs 60 stl
Waterwheel 100 stl
Windmill/Coal Fire 200 stl
Steam Pipes and Boiler 1,000 stl
Sun Mirror 2,000 stl
Part Group #4: Basic Frames
Stonework 5 stl
Wood Frames 10 stl
Iron Frames 20 stl
Part Group #5: Mechanical Components
Clockworks 30 stl

Reducing the Cost (Optional Rule)

By limiting the number of times that the device can be used before it becomes nonoperational, you can reduce the final cost of the device. This may be due to cheap parts that break down after a certain time, or perhaps a limited (and nonreplaceable) amount of fuel that is built into the device (perhaps there is no refuelling mechanism!). Once you have used the device a specific number of times, it ceases to function and cannot be repaired. However, you can rebuild the device from scratch, saving 50% of the steel pieces that were originally spent to build the device.

Table 3-B: Limited Use Gnomish Devices
Number of Uses Final Cost
12 80%
6 75%
3 50%
1 25%

Building the Device

The time required to build the device depends upon its size and complexity. According to the following table. Multiply the size of the device by its Difficulty Class and then refer to Table 4: Construction Time. Having additional gnomes assisting does not decrease the construction time (if you have worked with gnomes, you know why).

Table 4: Construction Time
Size x DC Time to Construct
1-3 1d10 x 10 minutes
4-10 2d20 x 10 minutes
11-25 2d20 hours
26-50 2d6 days
51-100 1d4 weeks
101-400 2d20 months
401+ 4d12 months

At the end of the construction period, the gnome character must make a Craft skill check to determine whether he has created the device as designed:

1d20 + Size modifier + Craft skill modifier
(Craft skill modifier = skill rank + Int modifier + miscellaneous modifiers)

If this check fails, the gnome character should make an Intelligence check (same DC as the device). A success indicates that the device simply fails; however, a failure indicates that the device suffers a mishap.

Success: This means that the device works as intended. It will move, inflict damage, send messages, heat food, make light, or whatever it was created to do.

Failure: The device totally fails to function. Any gnome whose level is equal to or greater than the Difficulty Class of the device can attempt to repair it (the modifier for Size applies). The repair time is two hours times the DC of the device. However, each time that a device fails, a -1 modifier is subtracted from the Craft skill check.

Mishap: The device does not act as the designer originally intended. The precise effects vary, but in general the referee should consult Table 5: Gnome Mishaps. A misfiring device may be repaired as above.

Roll 1d20; if the roll is equal to or less than the gnome's level, then the player may choose any result from the Table 5. Otherwise, apply the result rolled.

Table 5: Gnome Mishaps
1d20 Mishap Description
1-8 Needs Another Part
9 Communication Glitch
10-11 Improper Alteration
12 Unexpected Glow
13 Olfactory Malfunction
14 Unbearable temperature Change
15 Horrendous Sound
16 Uncontrollable Movement
17 Hazardous Malfunction
18 Pursuit
19-20 Explosion!

Note: The degree of any effect or damage caused by a misfiring device is often equated with its complexity (and thus, it's Difficulty Level). To find the magnitude of the specific effect involved, look on Table 1: Gnome Device Complexity. For example, if damage equal to a DC 6 device were inflicted, then 1d10 hit points of damage would be lost.

Needs Another Part

The device requires another device to be built before it can function properly. The new part must be a useful device in its own right and have a demonstrated use other than merely fixing the original invention. This second device must be built using the same rules as any other device.

For example, a gnome who gets this result while attempting to construct a catapult now declares that he must first build an automated can opener before he can finish the catapult. Of course, if a mishap occurs while building the can opener, the gnome may need to build yet another device…

Communication Glitch

If the device was designed to communicate, it will function in unexpected ways at the discretion of the DM. If the device was not meant to communicate, it will do so in an unexpected way. Options include sending messages directly to foes and enemies with perfect clarity; randomly changing messages in such a way that their true intent is never trustworthy; or only sending every second or third word.

Improper Alteration

If designed to alter an object, the machine will do so improperly. If it is not designed to alter an object, it will do so badly (at a level equal to DC minus 1d4) in an unexpected way. Options include reducing finished goods to their base elements; creating something of limited use in the current situation; or doing the reverse of its intention.

Unexpected Glow

The machine suddenly begins to glow so brightly that the operator and anyone within 10 ft. times the size of the object is blinded for 10 rounds. No other functions occur.

Olfactory Malfunction

If the device was designed to change the state of the surrounding atmosphere, it will have the reverse effect: machines designed to clear the air will pollute it, and machines designed to create fog may clear it). If not so designed, it will create a stinking cloud effect within a radius of ten times its Size rating in feet. The gas is produced as long as the machine continues to function, and remains for an additional 1d6 minutes thereafter.

Unbearable Temperature Change

If designed to create a certain temperature, the device will have the opposite effect (for example, an oven will refrigerate). If not, then the device will produce heat (50%) or cold (50%) to a degree equal to its Difficulty Class. This may result in the destruction of the machine itself should the temperature rise to the point of burning or melting its components.

Horrendous Sound

The device makes a horrible deafening noise within a radius of ten times its Size rating in feet. All creatures within this area must make a Fortitude saving throw (DC 15) or flee the area at one. Any who remain suffer a -5 penalty to attack and Armour Class until the sound ceases. The noise continues as long as the machine continues to function.

Uncontrollable Movement

Regardless of the intention of the device, it suddenly takes off on its own at a speed equal to its Difficulty Class. If the device was designed to fly, it actually digs or submerges; otherwise, it runs or flies in a random direction at a speed equal to its complexity. No directional control is possible. The device continues to move as long as it is turned on.

Hazardous Malfunction

The device inflicts damage equal to its Difficulty Class upon the nearest character, and then fails. The machine must be repaired before it can be used again.


The device attacks its operator for damage equal to its Difficulty Class and unerringly chases the operator for a number of rounds equal to 1d6+5 or until it is shut off, whichever comes first. The operator of the device must make a Dexterity check (DC 15) to turn off the device. The machine attacks with an attack bonus equal to its Difficulty Class.


The machine explodes, inflicting damage equal to its Difficulty Class to all creatures and objects within a radius of ten times its Size rating in feet. The machine is then broken and must be repaired before it can be used again.

Example Gnomish Devices


This was designed as a portable device that does damage to foes at a distance. This complex weapon is worn as a backpack and can throw a keg of volatile oil up to 300 feet away, causing 1d20 points of damage. It has six such charges before it must be rebuilt (this reduced its final cost to 75%; the gnomes did not consider the practicalities of a reloadable blamblower).

Type Effect Modifier
Damage 1d20 10
Move object 300 12
DC Modifiers Number DC
Highest modifier 12 12
Additional effects 1 1
Total: 13
Size Example Check mod.
5 Backpack -5


This is the gnomish answer to stairs: an automated way to get to one place to another quickly and with relative safety. The device uses a combination of catapults of various sizes and principles as well as nets, and launches a man-sized or smaller individual 600 feet into the air. The double-emergency backup sponge landing system is an extra option not included in the base price of the system, of course.

Type Effect Modifier
Move object 600 feet 13
DC Modifiers Number DC
Highest Modifier 13 13
Additional Effects 0 0
Total: 13
Size Example Check Mod.
11 Cottage +1


This gnomish invention is supposed to render an opponent temporarily immobilised from a distance and thus allow the attacker to possibly capture the opponent unharmed. Unfortunately the ultimate effect was all to often felt by the user of the device rather than the foe.

The netflinger, when it operates successfully, entangles any creature of Medium-size or smaller within 25 feet, just as a net does.

Type Effect Modifier
Restrain Medium 9
Move Object 25 feet 5
Duration 1-3 rounds 1
DC Modifiers Number DC
Highest modifier 9 9
Additional Effects 2 +2
Total: 11
Size Example Check Mod.
4 Crossbow -6


Original concept: a device to prepare meals. This labour-saving invention turns perfectly good raw vegetables and meat into an amorphous mass of steaming glop.

Type Effect Modifier
Temperature +300° 9
Alter objects Raw -> cooked 5
Information Clockwork 7
DC Modifiers Number DC
Highest modifier 9 9
Additional effects 2 2
Total: 11
Size Example Check mod.
6 Chest -4


The original concept was a device to transport a family of gnomes over a distance. This large wagon device is self-propelled but only goes 20 miles in the course of a three-hour period.

Type Effect Modifier
Speed 40 feet 6
Duration Three hours 11
DC Modifiers Number DC
Highest modifier 11 11
Additional effects 1 1
Total: 12
Size Example Check mod.
10 wagon 0

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