Well, this isn't what I was hoping for, but what I expected.
Clerics are in a weird spot at the moment. You could almost call it a crisis of faith. It seems like nobody really knows what they are supposed to be anymore. It used to be that they had a hard line of niche protection where they were "The healer, who could also pull warrior duties" and had access to not only the fastest way to restore hp, but a monopoly on any other way to fix the PC's. Later on the healer niche was eroded down a bit, and Clerics got spell power to compensate for it, leaving them in a state where they basically could do anything, if not everything at some points. Some people considered that a fair trade cause they were still the go-to walking band-aid dispenser, but most other people didn't. Their next iteration all but totally removed their healing niche protection, by spreading it over multiple classes and making it so nobody needed to be tethered to a healer in order to adventure at a decent pace in the first place. They still had a defined roll, but were now faced with the more important question of "How do I make myself valuable to a group that doesn't need me?"
Right now, the only unique mechanic they have is turn undead, which is not much to base a class on, even less so considering some of the Domains don't exactly seem like they should be able to pull that off in the first place. Their fluff is getting cribbed left and right. What is the point of having a class be a dedicated servant of the gods, when multiple other classes can pull that off, while still retaining their core identities? You could say people have an image of a default cleric, and from what I have gathered it's an unglamorous, unadventurous depiction of something modeled off of stereotypical clergy life. Candles and prayer books and sitting around the temple all day long. You could say it's like a wizard, but even the the bookish wizards have experiments and tomb raiding for lost magics to drive their adventurous spark. I believe the domain of the cleric is where their identity was supposed to happen, but the domains don't really fulfill that kind of thing. Partly because they fall into two distinct camps with recycled abilities, and partly because the skeleton of the cleric doesn't have much for the domains to cling to and modify.
That's enough of me rating in the dark hours of the morning about core Clerics. On to the Article itself. I'm tired, and cranky, and I risk making this sound more negative than I intend it to be if I keep going on like this.
Forge Domain
Become one with the anvil.
Spells:
You get some fire stuff and a potpourri of spells that target objects. Bonus spells are one of the things I like about domains, considering it's something that can make clerics function differently.
Heavy Armor Proficency
Well, this is another Basher, at least having heavy armor is unquestionably appropriate, unlike the nature domain. But why not martial weapons?
Blessing of the Forge
You get a +1 weapon for free until around level 6, and then you get +1 Plate for the rest of your adventuring days. This is front-loaded and boring, with a side putting strain on bounded accuracy. It is worth noting that you can use this on your allies gear too. Great for that one character who hasn't found a magic Hand Crossbow because the DM doesn't like Sharpshooter builds.
Artisans Blessing
A more thematic use of Channel divinity than Turning Undead at the very least. But why is there a GP limit if you are required to use materials that cost the same? Is making a suit of plate around the same time you could buy one really something that needs to be stopped? Right now it's primary draw is going to making forgeries (does that count as a pun?) of keys or nick-nacks so the cleric can act like a rogue. Which goes against the grain of what this subclass is trying to invoke.
Soul of the Forge
Defense Fighting Style, but way better. The construct damage bonus is a bit out of left field though. I understand the connection, I just think it's tenuous given the existence of Flesh Golems, and the situation is rare enough that lots of players are going to forget it even exists.
Divine Strike
It's fire damage on a weapon attack. It's there to make it so the cleric doesn't lag behind in melee combat. Basically every cleric that doesn't have Potent Spellcasting has this in some flavor. I don't love it, but that's mostly because I think it should be folded into the core cleric experience somehow. It's mechanically sound enough.
Saint of Forge and Fire
Now this is interesting, with lots of fun potential for things you can do, like burn the world around you while you sip on some tea. The non-magical restriction on the mundane damage types is unnecessary though. This Domain already has command over magic weapons, and high levels are rich with enemies that have magical weapon attacks.
Thoughts:
It's blunt. But it still has a few loose ends
Grave Domain
Because busting makes you feel good.
It's the Death domain for people who aren't trying to kill everyone, just the ones who are already dead.
Spell list:
Some of these are questionable. Such as Ray of Enfeeblement, Vampiric Touch, Blight, and Antilife Shell. So basically half of the spells.
Heavy Armor
This technically works, due to most of the "Drain your life" attacks require an attack roll, but it seems like these guys would be the ones to stay away from the reach of the nasty things trying to kill them. I honestly think this subclass should have gone down the caster route instead of the basher route to begin with.
Circle of Mortality
You are really good at stopping people from bleeding out. Thematic.
Eyes of the Grave
This has the same problem as the UA ranger, Information Overload. I'm thinking it should be more like Divine Sense from the Paladin.
Path to the Grave
It's very useful for killing things. Especially things that are resistant to multiple forms of damage. However, I can't help but feel this should be an Elemental Clerics shtick. Certainly not for basher clerics at the very least. On top of that, this is the one Domain where Turn Undead is the channel divinity power to have.
Sentinel at Deaths Door
A use for a reaction is nice. But why does this negate critical hits, instead of any of the nasty effects that undead are prone to throw about? Things like charm, fear, paralysis, disease, or stat penalties. That would be way more useful as a sometimes used ability.
Divine Strike
Why do undead hunters deal Necrotic Damage? Path to the Grave isn't something that is useful enough make this workable in the conditions that you would need it.
Keeper of Souls
I don't like the idea of using the enemies hit dice in this power. Mostly because I stopped using hit dice for monsters. But also because this is virtually unlimited healing. I think this should be tied to the recipients HD instead.
Thoughts:
So many questionable choices here.
Protection
Because Paladins are too smite happy for your defender needs.
Spells:
The only questionable one is Slow.
Heavy Armor Proficiency
Was there ever any doubt?
Shield of the Faithful
Why is this a mundane effect? This is a servant of the god of protection here, the least you could do is give them a ranged magical ward that helps them protect instead of relying on them to jump in front of every bullet like they are the secret service.
Radiant Defense
This isn't very defensive, one charge of damage when someone else gets hit? No defensive buff, or temp hps, or disadvantage, just an eye for an eye. The scaling is a bit weird on this too, how many damage effects use your class level in the calculation?
Blessed Healer
Healing isn't the same as protecting. Protecting involves preventing a bad thing from happening in the first place. Healing is just cleanup after the bad thing happened.
Divine Strike.
Why does this get radiant damage, and not the undead hunters? Is there no other damage type available for "protecting?" Do they even need to deal more damage considering they are looking to be a leader/defender hybrid that isn't a Paladin?
Indomitable defense
Now this is a protection ability. Pick your own resistance, and you get to bestow it upon someone else if you see fit. My only complaint is that it doesn't allow you to pick from every damage type in the game, as an endgame ability should.
Thoughts:
At least half of this domain just kind of exists. Which leads me to believe that it shouldn't have been a domain to begin with. I understand the draw of a defender cleric, this shouldn't be the way it happens though.