Introduced in Tome of Heroes, the Gunpowder property allows damage dice to “explode”, giving black powder firearms and items an element of excitement unique to those weapons. Rolling an exploding die is immensely satisfying, and having the same die explode multiple times is just a ton of fun.

If you’re nervous about Kobold Press’s Gunpowder rules, consider using the official Gunner feat. The black powder subclasses in Tome of Heroes were built around the Gunpowder property, so they’ll be greatly diminished without it, but if you weren’t going to use them in your current game that might be fine.

Table of Contents


RPGBOT uses the color coding scheme which has become common among Pathfinder build handbooks, which is simple to understand and easy to read at a glance.

  • Red: Bad, useless options, or options which are extremely situational. Nearly never useful.
  • Orange: OK options, or useful options that only apply in rare circumstances. Useful sometimes.
  • Green: Good options. Useful often.
  • Blue: Fantastic options, often essential to the function of your character. Useful very frequently.

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The advice offered below is based on the current State of the Character Optimization Meta as of when the article was last updated. Keep in mind that the state of the meta periodically changes as new source materials are released and this article will be updating accordingly as time allows.

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How Does it Work?


Kobold Press’s interpretation of firearms grants proficiency just like any other simple/martial weapons.

Loading and Ammunition

Each of the firearms in Tome of Heroes has the Loading property, with the exception of the Dwarven Revolving Musket.

The Loading property limits you to one attack per turn. Crossbows get around this with the Crossbow Expert feat, and typically firearms in 5e get around Loading with the Gunner feat. It’s not clear if players were intended to use the Gunner feat in conjunction with Kobold Press’s Firearms, but Tome of Heroes was planned, Kickstarted, written, and published all in a post-Tasha’s world, so I’m going to assume that the availability of the Gunner feat was considered.

The Dwarven Revolving Musket has an 8-shot magazine, the Kobold Press’s Magazine trait allows you reload as an Action or a Bonus Action, so it’s easy to fit reloading into your action economy. Even so, go into combat fully loaded.

Exploding Dice

I’m going to borrow some snippets of the text:

If you roll the highest possible number on an individual damage die… you can roll that die again and add the result to the total.

Any of the damage dice for this weapon, including extra dice such as from a critical hit or sneak attack, can burst and result in a reroll.

This adds a boost to the average value of an individual damage die as well as the incredible satisfaction of rolling exploding dice. Were that the entire text, you could hypothetically roll an infinite amount of damage if your luck held.

But there is a limitation:

For each attack… you can reroll only a number of burst dice equal to your proficiency bonus, regardless of how many damage dice result in the highest possible number.

If you’re thinking “it’s mathematically unlikely that even a d4 will explore more than twice”, you’re right. But this prevents hypothetical scenarios where you could roll an infinite amount of damage.

I was fortunate enough to talk about these firearm rules with Brian Suskind, who Kobold Press tasked with writing these rules, on the RPGBOT.News. Apparently there was some back-and-forth within the design team about whether the Proficiency Bonus cap was necessary, and I’m going to do my absolute best in this article (and in some subclass handbooks) to prove that it is.

Critical Hits

Critical hits in 5e double the damage dice. It’s unclear if you’re intended to roll twice as many dice or roll dice normally, then double the value. The results are the same on average, so it usually doesn’t matter.

But with Gunpowder, it suddenly matters a great deal. Doubling the actual number of dice rolled means twice as many chances to have a die explode, making critical hits with firearms very exciting.

Average Die Rolls

The Gunpowder mechanic’s exploding dice change the average rolls of each die. The table below assumes that you are rolling a single damage die and have a Proficiency Bonus of +6 for the maximum possible number of rerolls.

Regular AverageGunpowder Average

As you can see: It’s not a huge difference on a single die. Your fighter with a musket and a Sharpshooter isn’t going to break the math by switching from a longbow to a musket using Kobold Press’s rules.

But some weapons like the Blunderbuss and the Dwarven Arquebus deal multiple dice of damage, and any “extra damage” (additional dice dealing the same type as the weapon, such as Hunter’s Mark or Sneak Attack) can also explode, dramatically increasing your odds.

The math gets complicated so I’m not going to math out every scenario, but understand that you want to roll as many dice as possible to improve your chances of exploding multiple times. The most reliable scenario is to plan for dice to explode only once at most, but to have a whole bunch of dice.


It’s not entirely clear how the exploding dice are intended to work with rerolls, so I am doing some conjecture here:

Anything that allows you to reroll a damage die can be applied, potentially changing whether or not a damage die will explode. The rules for simultaneous effects allow the user to determine in which order they occur, so you’re free to reroll in between checks for whether or not dice exploded.

For example: Joe Pistolero can reroll one damage die on his attack. He fires his pistol, but only rolls a 4 for damage. He uses his reroll before checking if the die explodes, and on the reroll he rolls a 6. This causes the die to explode. In celebration, Joe fires his pistol in the air, this time rolling a 6 on the damage die and exploding on the first roll. The second roll is a 1, so he uses his reroll before checking if the die explodes. He rolls another 6, causing the die to explode again, maxing out his Proficiency Bonus of +2 and blowing a hole in the ceiling of the saloon.

Character Options


BugbearMMoM: Surprise Attack adds 2d6 extra damage, and those dice can both explode.

Half-OrcPHB: Savage Attacks only works with melee weapon attacks, which is absurd and pointlessly limiting. If you find a way to put Gunpowder on a melee weapon (Black Powder Domain Cleric), Savage Attacks gets you an extra damage die on a critical hit, which means an extra opportunity for an exploding die.


This section will only address classes generally and won’t dig into subclasses in any depth.

Artificer: Despite having access to firearms made explicit in their class features, the artificer doesn’t gain any unusual benefit from Kobold Press’s version of firearms. Since the Artificer isn’t published in the SRD, Kobold Press effectively needs to pretend that it doesn’t exist for legal reasons.

Barbarian: Barbarians are terrible with Dexterity-based weapons.

Cleric: With only one attack and no sources of “Extra Damage”, there’s little reason for clerics to use firearms. The Black Powder domain allows everyone to enjoy the mathematical wonderland that is the Gunpowder property, but the Cleric is among the worst characters for actually using anything with the Gunpowder property.

Druid: One attack, no source of “Extra Damage”, and a dubious relationship with metal.

Fighter: Perhaps the only character who strictly needs the Gunner feat, the Fighter’s high number of attacks will burn through the Dwarven Revolving Musket’s magazine too quickly at high levels, especially with Action Surge, so the action cost to reload quickly becomes a problem. But with the Gunner feat in hand, you’re free to grab a Dwarven Arquebus and rain exploding death on everything in range.

Monk: The Dedicated Weapon Optional Class Feature makes using firearms a possibility. Weirdly, the Monk’s Martial Arts die progression makes it less likely over time that your dice will explore.

Paladin: Paladins don’t do well with range combat.

Ranger: Extra Attack, Fighting Style (Archery) for more accuracy, and Hunter’s Mark adds a d6 of Extra Damage which can explode. You’ll do fine sticking to a Darven Revolving Musket, but if you take Gunner and upgrade to the Dwarven Arquebus you can deal 3d6 damage per shot, giving you a 42% chance per attack to explode at least once.

Rogue: Sure, you only get one attack and it’s likely with a pistol, but Sneak Attack dice are “extra damage”, so they can explode. Your pile of explodable dice will easily compete with fighters and rangers despite only getting one attack, and at high levels other classes will struggle to match you over an extended period since you can Sneak Attack literally every round.

Sorcerer: With the exception of Black Powder Sorcery, there is no reason for you to use a firearm.

Warlock: A hexblade can do just fine with firearms. Hex’s damage is additional necrotic damage, not “Extra Damage”, so it can’t explode.

Wizard: You’re not using a firearm for damage output. School of Black Powder uses a firearm more magical utility, not for explody damage nonsense, and the Bladesinging is no more effective with firearms than anyone else.


Fighting InitiateTCoE: Dueling will apply to one-handed weapons like the pistol, but you’re here for Archery for the +2 to attack rolls. An attack bonus improves your damage output multiplicatively.

GunnerTCoE: Use firearms in melee and ignore the Loading property. Most characters will do fine with the Dwarven Revolving Musket, but this allows you to switch to the Dwarven Arquebus, which has much better damage, including two damage dice instead of one.

PiercerPHB: Firearms deal piercing damage. See “Rerolls”, above, for a discussion of how the reroll works, and our Practical Guide to [Damage]er Feats for more on Piercer.

Savage AttackerPHB: I really wish this wasn’t limited to melee attacks. Piercer would still be massively better, but it would be nice if this weren’t just outright useless.

SharpshooterPHB: Be cautious here. If you miss, your dice can’t explode. If you’re okay gambling on missing, maybe stick to bows and crossbows.

Stunning SniperToH: Unless you’re building to fish for critical hits, don’t bother with this. Critical hits are too infrequent. The effect is amazing, but you’ll go a long time between critical hits so it frequently won’t matter.


Enlarge/ReducePHB: Enlarging the target adds +1d4 extra damage to their weapon attacks, including with ranged weapons.

Hunter’s MarkPHB: 1d6 extra damage. The die can explode, so this is an excellent addition for any firearm user.

Example Builds

  • Bugbear Assassin Rogue: Turn 1, draw a pistol and shoot something with it. You’re rolling 3d6+Sneak Attack+flat modifiers, and every one of those dice can explode. Depending on how your group handles critical hits (see above), you might double the number of dice on that near-guaranteed critical hit on turn 1, dramatically improving the likelihood of exploding dice. Add in the Piercer feat, and you get to reroll one of the dice on that attack, potentially causing it to explode.
  • Samurai Fighter: With Action Surge and the ability to make up to 4 attacks per Attack action, the Fighter can put out a lot of damage. Grab the Gunner feat, the Piercer feat, and a Dwarven Arquebus. Use Fighting Spirit to give yourself Advantage, activate Action Surge to make a second bunch of attacks, and start shooting. If someone casts Enlarge/Reduce on you, you’re rolling 2d6+1d4+whatever flat modifier. Piercer allows you to reroll one damage die per turn, so between all of those attacks you have a great chance for many of them to explode. If you want to go extra hard, Elven Accuracy makes you more accurate and more likely to score a critical hit, which is nice because you add an extra damage die from Piercer, and depending on how your group handles crits, you might double all of the existing dice. Add Sharpshooter, and what would already be a very powerful build without Gunpowder adds the likelihood of exploding dice.