Draconic Powder Horn (Patreon)

Wondrous item, rare

This dragon's horn is filled with a dark, explosive powder. Either end of the horn can be opened, allowing for either precise or rapid emptying. The horn can hold enough powder for up to 20 uses. While holding the horn, you can use an action to speak its command word (typically "fire" in Draconic), creating a small spark from its narrow tip and allowing it to be used as a tinderbox.

You can open or close either end of the horn (no action required) to pour out some of the powder in either of the following ways.

Large End (Rapid). As an action, you pour out 1d10 + 5 uses of the powder from the horn into a small pile, up to the number of uses remaining. The pile settles on the ground at a point within your reach. If the powder takes any fire damage or catches fire, it erupts into a fiery explosion. Any creature within 15 feet of the pile must succeed on a DC 15 Dexterity saving throw or take 1d4 fire damage for each use of the powder in the pile. A creature that fails the saving throw by 5 or more is also knocked prone. On a successful save, a creature takes half as much fire damage. The explosion spreads around corners, and it ignites any flammable objects in the area that aren't being worn or carried.

Small End (Precise). As an action, you pour out a narrow line of the powder from the horn that's 1 inch wide and 5 feet long within your reach. It takes 1 use of powder to make a 5-foot line. If you use this action and then move, the line continues along your path: for every 5 feet you move, another 5-foot line of powder is poured, up to the number of uses remaining in the horn. If the powder takes any fire damage or catches fire, each consecutive 5-foot line immediately erupts into a vertical wall of 5-foot-tall flame. The wall remains for 1 round: any creature that starts its turn within 5 feet of the wall or that moves through it for the first time on its turn must immediately make a DC 15 Dexterity saving throw. A creature takes 3d6 fire damage on a failed save, or half as much damage on a successful one. The wall ignites any flammable objects within its area that aren't being worn or carried.

Once a use of the powder catches fire, it's lost. Otherwise, you can spend 1 minute recovering a poured-out use of the powder, replacing it in the horn when you do. A creature can use its action to smudge out some of the powder within its reach: either 1d6 uses from a pile or a 5-foot-long section from a line. Doing so destroys that powder.

The horn regains 1d10 + 10 poured-out uses of powder daily at dawn, at which point any poured-out powder turns to ash. If you use the horn to light either a pile or line of the powder, you can choose for the spark to smolder harmlessly until the start of your next turn, at which point the powder catches fire and explodes.

The chemist slunk along the wall, a thin trail of powder following him. Every 10 paces, he placed a small red cube of goo. After his placement was done, he scurried back, avoiding the guards' gaze from the parapet. At the foot of the wall, near its center, he opened his powder horn and dumped out a pile, cursing slightly as more was poured out than intended. He capped the horn and took the dragon head stopper out of the bottom.

He whispered something raspy and strange, Draconic, and then bolted to the trees. The guards spotted him and shouted, but it was too late. A few seconds went by, and a powerful explosion shook the wall, cracking it—the second blast a moment later tore it down.

His job was done, so hopefully his friends could do theirs.