Machine Domain

There are some gods who are inventive and creative, who not only wield craftsmanship and magic, but do so with the usage of magical machinery. Gnomish dieties, some Dwarven deities, Goblin deities, and human deities have commonly had gods wield such forms of device and artifice, whether for good or for evil ends. This domain encompasses the common magic of machines and the spells that assist in the working spaces of machines. As they advance in knowledge of machine magic, they develop a divine machine they carry with them as a sort of magic holy symbol which can transform for multiple functions of usage, and perform multiple mechanical tasks with deft capability, from attacking to defending, to being many useful tools as needed, or to assisting in casting magic more potently. At their apex, these clerics wield powers which employ some of the most capable and powerful machines anyone has ever seen... divine battering rams, magic barrier fields projected from rolling armored wagons, tools which can silently perform any task on their own in a matter of seconds, and many more incredible devices. In history, it is gods like Hephaestus, Hermes, Thoth, Osiris, and Heimdall that have utilized machines and magical artifice to this degree.

Domain Spells

1st-level Machine Domain feature

You gain domain spells at the cleric levels listed in the Machine Domain Spells table. See the Divine Domain class feature for how domain spells work.

Machine Domain Spells

Glorious Gearhead

1st-level Machine Domain feature

At 1st level in this class, you learn the basics of using magic to assist when you apply your skill to your usage of tools and machines. You gain proficiency in Tinker's Tools, and when you have them in hand, you can cast the Mending cantrip. When you cast the Mending cantrip, you gain advantage on the next tool use check you make for the next 1 minute afterward. 

Additionally, you may choose any two armors, weapons, or tools that you do not have proficiency in, and you gain proficiency with both.

Channel Divinity: Halt Process

2nd-level Machine Domain feature

At 2nd level in this class, you learn to channel divine power to halt machinery and mechanical processes, freezing them into an inert state to prevent any tremendous failure or disasters. As an action using your Channel Divinity and with your Holy Symbol or Tinker's Tools in hand, you may choose any machine or construct within 50 feet of you and make a spell attack roll to hit it with a beam of stasis energy. If you hit, the machine stops suddenly and safely and becomes inert and motionless, or the construct creature has their speed reduced to 0 and is restrained for as long as you maintain concentration, as if concentrating on a spell. Flying constructs affected by this stasis beam fall out of the sky from their current height, taking falling damage.

Divine Machine

6th-level Machine Domain feature

When you reach 6th level in this class, you come to understand how divine power can make a machine operate miraculously to the expectations of the device, and you can craft your own such magical device. With Tinker's Tools in hand and using 200 gold pieces of supplies, you spend 1 hour to craft a Divine Machine. A Divine Machine may have one of the following properties:
Artillery: as a bonus action, the Divine Machine belches forth a blast of fiery energy to harm your foes, which uses your spell attack roll to hit a creature within 50 feet, and deals 2d8 fire or radiant damage (your choice when you build the machine).
Defense: as a bonus action, the Divine Machine energizes a small area with a defensive force shield, and a number of creatures of your choice up to your Wisdom modifier (minimum 1) within 10 feet of the machine gain 2d8 temporary hit points. These hit points last for a number of rounds equal to your Proficiency Bonus.
Tool Type: as a bonus action, the machine becomes any set of tools you choose and you are treated as if you are proficient with these tools as long as they remain in your hand or you are touching the Divine Machine. If it is a small machine, you may use your action to command it to perform the tool use check within 5 feet of it, and you can make the tool use roll at the location of the machine, using your bonus.
The Divine Machine can transform to have a different one of these properties if you spend a short rest concentrating on the machine with your Tinker's Tools in hand. The Divine Machine you create is treated as your choice of a tiny or small object. A tiny machine can be carried and utilized in one hand, and a small machine can locomote itself along the ground on small legs or rollers to magically follow behind you at your speed, going no faster than speed 30, It has AC 15 and a number of hit points equal to twice your Cleric level. You can command a small machine to move its speed as a bonus action on your turn, and if it is ever greater than 300 feet away from you, it will move its speed to return to within 5 feet of you without using any action to command it on your turn.

Additionally, you can use any attuned amulet as a focus for your spellcasting.

Potent Spellcasting

8th-level Machine Domain feature

Starting at 8th level, you add your Wisdom modifier to the damage you deal with any cleric cantrip.

Machine Mastery

17th-level Machine Domain feature

At 17th level, your divine skill with mechanical devices and their properties is entirely legendary, and you can make constructs and machines perform miraculous things. Whenever you cast a spell using Cleric spell slots, you gain a Machine Die. You can have a maximum number of Machine Dice equal to your Proficiency Bonus, and when your Divine Machine or a construct under your control deals damage or bestows temporary hit points to a creature, you can roll and expend these Machine Dice to add to the totals of both such rolls.

Additionally, whenever you cast the Summon Construct spell, if you possess a second ornate lockbox in your hands when you cast this spell, you can summon one additional construct creature casting this spell a second time as part of the same action without expending a spell slot if the type of construct you choose is metal material. Both constructs made of metal will appear in range as you choose when you cast this spell this way, both may be commanded verbally at once, and both remain for along as you maintain concentration.

Lastly, you add "Create Homonculus" to the Cleric spell list and can prepare it as a Cleric spell. When you create this homoculus, you can bestow upon it proficiency with any one weapon, armor, or tool. It uses your Proficiency Bonus + your Wisdom modifier to make those attack rolls or skill checks on its turn when commanded instead of any other bonus.