Weaklings in Tin Cans
One of the great things about D&D is that it provides fans with many different wild and wacky ways to express themselves. Reading through this I was struck with the kind of superhero imagery that you'd expect – a suit of powered armour that can shoot lightning bolts and magic missiles and enhance your vision to the point where you have a built-in danger system. However it also really struck the vibe of gnome engineers clumping around in suits big enough to be considered vehicles (but still shorter than their party members because size is a thing), with hastily constructed weapons flapping around on their shoulders, flouting whatever health and safety laws fantasy worlds do or don't have in the process.
There is a huge amount to get through here (which may be the pattern for Artificers going forward) so buckle up, this may be a long read...
Each of the features below includes a summarised reference to the rules in the Unearthed Arcana article but it's worth downloading the full, free PDF from the Wizards D&D site, here.
Tools of the Trade - 3rd Level
Proficiency with heavy armour and Smith's tools.
You wanna build the doohickies you need the tools. 'Nuff said!
Armourer Spells - 3rd - 17th Level
Nothing seems particularly broken here. It's worth noting that the Shield spell is one of the things you can get hold of at level 3, though, which feeds into quite a few of the abilities to come and hints strongly at the play style this subclass is shooting for.
Power Armour - 3rd Level
If you have smith's tools, a suit of heavy armour you're wearing loses its Strength requirement, becomes your spellcasting focus, replaces any of your lost limbs and can't be removed against your will.
Technically you're supposed to be wearing the armour and have your Smith's tools in hand to turn a suit of heavy armour into Power Armour, so heaven help you if you have to tweak something at the back! This ability allows your Artificer to wear plate armour and still function, which is always a good thing. Both of your hands will remain free when casting spells (also useful). If you've lost limbs by 3rd level you've either written a tragic back story, played very recklessly or have a savage DM, so this will fix that nicely. People not being able to take off your armour against your will is of course very handy if you're captured.
And also, consider this: you can no longer be pantsed.
Armour Model - 3rd Level
Choose Guardian or Infiltrator. You can change your mind after a short or long rest if you have your Smith's tools.
Guardian: Your fists become melee weapons that deal 1d8 thunder damage each and cause any enemy you hit to have disadvantage on their attack rolls if they attempt to attack anyone other than you until the start of your next turn. As a bonus action you can gain Temporary HP equal to your Artificer level, overwriting any Temporary HP you currently have.
First of all, pickle my pauldrons do you get a lot of stuff at 3rd level! The other levels are surely envious! Other classes' 3rd level advancements certainly are! Spells, bonus proficiencies, armour bonuses with special rules... I would not have been surprised or upset if, after writing up these rules, there had been a little note that said “sorry, but you got it all at level 3, that's the last you get from this subclass.” But no, it keeps comin'!
The Guardian option for this feature doubles us down on the tanky artificer. Giving opponents disadvantage on their attack rolls against other members of the party except for you is the 5e equivalent of the aggro mechanic, it seems. It's worth noting two things – first of all, even though both of your fists count as melee weapons, they don't count as light melee weapons, so you can only attack with one of them at level 3 (you'll need to take/have taken a Feat to switch this on). Secondly, if anyone else in your party has an ability similar to this (such as an Ancients Barbarian) then if you're fighting just one opponent, you have a real shot at just applying disadvantage to all of their attack rolls as both of your “disadvantage attacking anyone else” mechanics kick in.
Not being able to use both fists to attack doesn't seem so bad when you look at the ability to gain Temporary HP as a bonus action, however. At level 3, this may not seem like the greatest thing in the world, but 20 Temporary HP per turn at max level is nothing to sniff at. Granted, that 20 HP might not soak up an Ancient Dragon's breath attack, but it will definitely have a shot at keeping you away from dead for a much longer time.
Infiltrator: The armour no longer gives you disadvantage on stealth checks if it did before. You get +5 feet of movement. Your chest or fist becomes a ranged weapon that deals up to 2d6 lightning damage on a successful hit.
This time, you're not so much a 'traditional' tank as an 'IRL' tank, what with being clad in a thick layer of metal and in possession of a large gun. This reminds me of the gun that the OG Unearthed Arcana Artificer had and I don't know if that was the intention, but it's a cool nod in that direction if so.
Extra Attack - 5th Level
Attack twice instead of once whenever you take the Attack action.
Because people say “pew pew” more than they say “pew”. One “pew” seems a bit lacking, you know? But it's OK, because at level 5 you don't have to worry about that any more.
Armour Modifications - 9th Level
Your armour now counts as four separate items for the purposes of your Infuse Items feature, and you can infuse up to 2 more items, as long as the bonus infusions are applied to pieces of your power armour.
As anyone who's ever done re-enactment will know, armour doesn't just come in one piece with a hinge at the side, it's a whole bunch of smaller pieces that you have to don separately. This may mean more work getting dressed, but at 9th level it means you can add an infusion to each different piece (in the broadest of terms) separately – chest, boots, bracers, weapon. (The “weapon” part of that refers either to your thunder fingers or thunder solar plexus, depending on whether you're a Guardian or an Infiltrator). You're also allowed to use 2 more infusions, as long as the bonus 2 are pieces of your power armour.
This seems pretty strong – having an additional 2 things above and beyond other Artificer subclasses seems like it could be a touch unfair but it does come at the price of not having anything more spectacular at level 9, so I think it balances out fairly well. There are some more infusions to choose from too, which will be covered a little later.
Perfected Armour - 15th Level
Guardian: If a creature ends its turn within 30 feet of you and you can see it, you can use your reaction to make it take a Strength save. If it fails, you can pull it up to 30 feet to a space within 5 feet of you.
We talked about aggro mechanics earlier – this is a taunt mechanic... kind of. The creature has ended its turn by the time this happens, so the taunt is belated, but you definitely get to move it away from your friends and hit it with those sweet electric gauntlets (giving it disadvantage to attack anyone other than you), so you do at least get some degree of control!
(Yelling “GET OVER HERE” will never not be acceptable. “Engage tractor beam” also gets a pass.)
Infiltrator: A creature you hit with your power armour's ranged weapon glimmers with light until the start of your next turn. The next person to attack it has advantage and deals an additional 1d6 lightning damage.
Kind of like a poor man's Faerie Fire + Hunter's Mark, but then Rangers everywhere would be in tears if you trampled on their gimmick too hard...
New Artificer Infusions
Armour of Magical Strength (10th Level, Suit of Armour, Attunement)
Use Intelligence score for Strength checks and saving throws. You can avoid being knocked prone 4 times per day.
This seems like a reasonable ability to have and will be particularly useful if you really are the only beefy character in your party (especially if you dumped Strength and are relying on your Armourer subclass features to keep you in plate).
Armour of Tools (Suit of Armour)
Add a set of tools to your power armour. Use your Intelligence modifier when you use those tools.
From Power Armour to Power Tools. The ability to use Intelligence when using your tools seems better than integrating them into your armour, although it will definitely stop you from dropping your tweezers down a storm drain. We all know how annoying that is.
Helm of Awareness (10th Level, Helmet, Attunement)
You have advantage on Initiative rolls and you can't be surprised unless incapacitated.
This is not the only way to gain this particular feature, but if this doesn't flash a big red light saying “THIS SUBCLASS IS FOR TANKING” then probably the message is just going to fall on the stony ground and stay there, crying, while you attempt to tank with an Alchemist.
Mind Sharpener (Suit of Armour or Robes)
If you fail a Constitution save to maintain concentration, you can use your reaction to pass it instead.
You can use your reaction to what now?
Were it not for the fact that there are so many things to use your reaction for (Shield, grabbing something and hauling it across the battlefield, attack of opportunity if the thing you grabbed tries to escape) then I would probably raise both eyebrows at this, but I'm currently only raising one. Being able to just do this once a round if you're not flush with all of those choices is... pretty darn strong. But then, I guess if the DM really wants your concentration broken, they can just attack you with everything, and that will be where my final eyebrow returns to its normal, resting position. Otherwise it's staying raised!
Spell-Refuelling Ring (6th Level, Ring, Attunement)
Once per long rest, use an action to regain a spell slot equal to the number of magic items you are attuned to.
This seems OK for 6th level – Sorcerers can swap Sorcery points for spell slots more effectively than this, so it seems like a nice gimme for the Artificer without stepping on anyone else's toes.
As you'll be able to tell from the introduction, this is another big success from my point of view where flavour is concerned, and it's a great addition to what the Artificer can do. I think you do get an awful lot at level 3 but despite the amount of rules text, I don't really feel too much like it's broken. I also like that tanking is now something an Artificer can feasibly do.
One thing I would say (and that you may have noticed from everything after the introduction) is that I rate the Guardian version of the armour much more than the Infiltrator version. The Infiltrator features aren't bad, but they seem a bit... meh in comparison. Guardian knows what it wants to do, but with Infiltrator you sneak around with your lovely non-clanky armour to... shoot a massive beam of lightning at someone? I'm fairly sure that would give away your position pretty quickly...
All in all, though, this looks like a lot of fun and I hope it finds its way into D&D canon!