Incendiary shell

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Incendiary shell

Incendiary shell

A shell filled with flammable gel and a small explosive charge. Starts fires when detonated. Can be fired from mortars or installed as a trap. Explodes when damaged.

Base Stats

Crafted ResourcesMortar shell
Tech Level
Market Value
55 Silver
Stack Limit
1.25 kg
Deterioration Rate
Path Cost

Ranged Combat

10 dmg (Flame)
41 (m/s)
Blast Radius


Crafted At
Machining table
Required Research
Skill Required
Crafting 4
Work To Make
800 ticks (13.33 secs)
Resources to make
Steel 10 + Chemfuel 20

The incendiary shell is a type of mortar shell that explodes into a conflagration, dealing flame damage and setting the area alight.


Incendiary shells can be crafted at a Machining table once the Mortars research project has been completed. They require Steel 10 Steel, Chemfuel 20 Chemfuel, 800 ticks (13.33 secs) of work, and a Crafting skill of 4. The steel cost is increased to 20 if the Classic Mortars difficulty option is enabled.

They can also be purchased from traders.


When fired from a mortar, incendiary shells deal 10 Flame damage in a 2.9 tile radius. They also set the area on fire and creating chemfuel puddles which themselves burn.

When damaged beyond 70% of its health, it will explode after between 30 ticks (0.5 secs) and 60 ticks (1 sec), dealing 10 Flame damage in a radius around itself. The radius depends on the quantity in the stack, with a single shell covering a 2.9 tile radius, and expanding this radius proportional to the square root of the stack size times 0.4 up to a maximum radius of 6 tiles at a full stack of 25.

They are also used in the construction of IED incendiary traps.


Incendiary shells are most useful against sieges - stationary targets with explosive mortar shells to light on fire. The fire makes it more likely to "hit" an explosive target than regular high-explosive shells, but watch out for firefoam pop packs.

Otherwise, incendiary shells are of limited use. The other "main" target of mortars, stationary mechanoids, are completely immune to fire. For ordinary raids, fire spreads too slowly to be useful in combat. As mobile raiders are smart enough to avoid fire, only a direct hit would cause damage. This makes high-explosive shells superior, as they deal much more damage on direct impact. Note that the game will automatically cause rain if fires get too far out of control.

Sieges can and will use incendiary shells against you, which will ravage through rooms floored with carpet, hay, storage rooms filled with flammable items. Firefoam poppers are very strong at protecting against fire.


As with all explosive items, these should be stored in separate storage containers. For maximum protection, put each stack of shells in a separate 1x1 stone box to prevent chain reactions. Pawns currently in a tantrum should be stopped at all costs, whether it be by arresting, creating another stockpile zone with a higher priority than the shell zone and prioritizing hauling the shells, or simply by shooting the pawn.


Version history[edit]

  • 0.18.1722 - Added to replace mortar type system.
  • 1.1 - crafting cost was increased (15 --> 20 steel and chemfuel cost).
  • 1.3.3066 - Steel requirement decreased from 20 -> 10 unless Classic Mortar difficulty option selected.