The Gunpowder Domain is not a domain in the standard sense, but a method that many temples use to arm their inquisitors. Most common among gods of Arcana, Knowledge, and War, a cleric of the Gunpowder Domain uses mystical firearms to smite enemies of the faith.

Gun Priest

From 1st level, your temple has taught you the secret of forging firearms. You gain proficiency with smith's tools and firearms.

With access to a suitable workshop, you may craft a pistol for 125 gp worth of materials and 1 week of work or a musket for 250 gp worth of materials and 2 weeks of work. You may also craft ammunition, even while adventuring, able to craft 10 rounds of pistol or musket ammunition over a short rest and 40 rounds over a long rest at a cost of 1 gp of materials per 10 bullets.

The mystical nature of your weapon's creation allows your faith to guide your attacks. Whenever you finish a long rest, you can touch one firearm that you have created. When you attack with that weapon, you can use your Wisdom modifier, instead of Dexterity, for the attack and damage rolls. This benefit lasts until you finish a long rest.

Channel Divinity: Rapid Fire

Starting at 2nd level, you can use your Channel Divinity to fire quickly with exceptional aim. When you take the attack action with a firearm, you may use your Channel Divinity to attack twice with advantage on both attack rolls.

Sacred Artillery

Beginning at 6th level, you can ignore the reload and loading properties of firearms and any firearm you craft has its misfire value reduced by 1. In addition you may create a Hand Mortar (Exandria) for 500 gp of materials and 4 weeks of work. You may use Alchemist's Fire (flask) as ammunition or create your own. Each shell costs 25 gp worth of materials and you can create one shell during a short rest or 4 shells during a long rest.

Divine Arms

At 8th level, you gain the ability to infuse your firearms with divine energy. Once on each of your turns when you hit a creature with a firearms attack, you can cause the attack to deal an extra 1d8 radiant damage to the target. When you reach 14th level, the extra damage increases to 2d8.

Suppressive Fire

At 17th level, when you Channel Divinity to Rapid Fire you may instead make a single attack with advantage against each creature of your choice within 60 feet. Creatures you target that are not behind cover must make a Wisdom save against your spell save DC or be frightened until the end of their next turn.