Let's get this out of the way first thing: the Arcane Propulsion Arm is pretty much inarguably the coolest thing to come out of the Eberron Rising book.  Half the artificers in the game have the end objective of obtaining one, and there will be people chopping their own arms off to gain access to it.  It's just that cool.

But as I'm sitting here tinkering with an up-leveled copy of my own artificer, I find myself wondering if maybe it's just cool, rather than as effective as it's cracked up to be.  And because I'm bored on my lunch break, figured I'd ask you lot, as well.

Pros:
-You cannot be disarmed.  Tee hee insert giggle puns here, but seriously.  The limb cannot be removed against your will, and in most games magic items tend to be absurdly durable.  Depending on how closely the artificer player and/or DM interpret the words "form a copy of the limb it's replacing", the APA cannot even be detected as a false limb by casual inspection (though this is no fun).  Unless someone convinces or coerces the character into voluntarily surrendering the arm, you will always have a weapon.
-Force damage.  Force damage is really good, and beats most other damage types you could access.  You can easily blast past most forms of resistance, dealing full damage to effectively the entire Monster Manual.
-Versatile.  As in actually versatile, not versatile.  The same weapon works equally well in melee combat and (short range) distance fights.  The rocket punch attacks are valid for Sharpshooter, which extends the range significantly and amplifies damage via Aimed Shot bonus.

Cons:
-Low damage.  1d8 force with your naked monkey fist sounds awesome...until you remember that by the 14th level at which most artificers would gain it, equivalent characters are going to be using weapons with equivalent damage die alongside numerous damage-boosting features, as well as stuff like Flametongues, Frostbrands, and various homebrewed gear with extra damage die or bonus damage.  Without Sharpshooter, your damage as a Battlesmith is low, and your damage as anything else is laughable.
-Attunement.  Specifically, the APA does not share attunement with any other prosthetics you may end up with the way normal Prosthetic Limbs do, requiring you to attune specifically to the APA.  if you do not, you're down one arm.  Effectively this permanently consumes one of your attunement slots.  Less of an issue for higher-level artificers, especially as comparable weapons generally also require attunement...but you can unattune a Flametongue and still have two hands.
-Feats.  Outside Sharpshooter shenanery (and some DMs would rule that Sharpshooter doesn't apply to rocket punching), the APA is not compatible with any of the combat-enhancing feats in the game.  As those feats are often considered absolutely mandatory for anything trying to do viable damage at higher levels, this leaves you out in the cold.

Given all this, the Arcane Propulsion Arm strikes me as being (while unbearably cool) a little bit of a trap.  An artificer trying to fight effectively with the APA would almost certainly do higher overall damage with a regular magical weapon.  Even if they haven't found a better one, Repeating Shot on a heavy crossbow produces 1d10+1 damage per shot rather than 1d8, if of a less favorable damage type, and has enormously better range.  And you can do that from level 1.

Make no mistake, my artificer is already drafting plans for an APA in her game and will continue to do so until either she can make it or the campaign dies and I can't play her anymore...but does anyone else find themselves wondering if it's all it's cracked up to be?  Or more likely, what they can do to spice it up a touch after some horsetrading with the DM?

It's enough of a trap option that I don't think I'd bother with it personally. But it IS undeniably cool and I can't fault you at all for going for it.

Since it still counts as a free hand if you need to you can still use it with another ranged or melee weapon using the APA as a back up option. Plus there's a reasonable argument to be made for it working as a 20 or 60 ft mage hand.

My current ideal for an infused item that can't be unwillingly removed would be the Ventillating Lungs (although I suppose surgical extraction isn't technically ruled out...).

Something further to note is that at level 14 Magic Item Savant opens up the Warforged only attunement items the Armblade and the Wand Sheath. Armblade is limited to one handed melee weapons but it doesn't exclude versatile weapons so you could get that d10 but it wouldn't be force damage. Sadly it doesn't look like you can choose existing magic weapons for your armblade like you can do with a wand sheathe at least not RAW.

Although there's nothing really said about what the APA can or can't be holding when it's thrown... So if your APA is holding a hand crossbow when thrown can it also fire it as the 2nd attack with Extra Attack?

Shit, I didn't even realize that "warforged only" was one of the things Savant ignored.  Admittedly, mostly because our home games already tacitly ignore that restriction for characters with prosthetic limbs - the limb is disadvantageous enough, and the armblade mild enough, that there doesn't seem to be any great reason to deny a character the option other than "Not RAW?  No dice".  Heh, that and even with the 'ignore race restrictions' from Savant, I feel like armblades and wand sheathes aren't going to work for a 100% fleshy artificer, regardless of what RAW says.  Srsly - ouch.

I suppose the counterbalance to all this is that if you already have one prosthetic limb, the APA is strictly an upgrade - you're sacrificing an attunement slot to regain full functionality either way, and the APA has some baller additional functionality built into it.  If it's an Infusion and not a regular item, you can also use it as a spellcasting focus, though there's easier ways to get "bare-handed" casting.  Gloves of Thievery, for one.  Everybody knows the regular prosthetic limb is pretty strictly flavor and is otherwise almost entirely inferior to just keeping your original monkey paw, but if you've already gone down that rabbit hole, there's little reason not to try and eventually get the upgrade.

Wands sheathes are super baller though, and I admit - if I can connive my DM into letting me design my own magic items, an APA with an integrated sheath would be at the tippy-top of the list.  At that point you have a wand that cannot ever be taken from you against your will (arm cannot be removed, sheath cannot be removed from arm, wand cannot be removed from sheath) and the Wand Sheath does not specify whether or not it's immediately visible.  One could very much argue that the sheath is integrated into the structure of the arm and cannot be readily discerned from casual inspection.  Close as you're ever going to get to a cyberpunk implanted firearm without homebrew.

As for treating it like a mage hand, or allowing it to wield shit...I dunno.  As a player, of course, the idea of being able to remotely control a flying drone hand is amazing and honestly turns my opinion of the item around - if that level of functionality is on the table then there's Decisions To Be Made - but as a DM I'd be super hesitant to allow it and even my player side is inclined to agree with my DM side.  The item as written states "flies out, punches fool, flies back", and the intent is screamingly clear.  There's an argument to be made for it to function as an independent drone, yeah - but there's an argument for saying "it's a rocket punch, not Permanent Mage Hand", and I feel that one is generally going to be stronger.  Same with performing fine manipulations while rocket punching, such as firing a crossbow.

'Course, no DM can really argue that the thing can hold a flask of alchemist's fire or acid before flying violently at someone's face.  Or stuff a bag of caltrops/bearings in a glass jar and deliver them directly to your enemy's location that way.  Obviously your DM would have to rule that your magic robot hand's immune to fire/acid for the former, but there's no real argument in my mind that it works.

It's a total trap.

Oh, Ackbar.  How poorly the memes have treated you.

Heh, after an interesting talk with the DM for my artificer, I've been hashing out possible rules for Mage Hand-ing the APA.  Not necessarily because I'm gonna do it as because it's fun just to puzzle out the mechanics and see how they'd work.  Figured people might have some fun poking holes in my work.  The following draft is added to the APA if a DM is up for shenanery:

"The Arcane Propulsion Arm can detach from you and hover near you.  In this state the arm is considered to have a Strength score of 4, but otherwise follows your commands as if it was still attached to you.  It uses your ability scores and skill bonuses, adjusted for its reduced Strength.  You can command the arm to move and act at any location within sixty feet of you, but you have disadvantage on any ability check made with the arm when it is more than 20 feet away from you.  At any time while the arm is detached in this way, you can command it to execute its rocket punch attack, after which it returns and reattaches as normal.  The arm can be used in this way for up to one hour, in increments no shorter than one minute, and regains one hour of use time for every twelve hours spent attached to you.  The arm can make its normal rocket punch attack without interrupting these twelve hours."

"While detached from you and acting autonomously, the Arcane Propulsion Arm can be attacked or seized by other creatures.  The limb has an AC of 13 + your Dexterity modifier when detached; if successfully struck, the limb flies back to you and reattaches itself, and cannot be detached again for a number of minutes equivalent to the damage roll of the attack (this includes making its rocket punch attack).  To seize the limb, a creature makes a Sleight of Hand check, with a DC equivalent to 8 + your ranged weapon attack bonus.  if successful, the creature captures your arm.  The limb is grappled, restrained, and moves with the capturing creature at no penalty to its speed.  As an action, you can command the limb to try and break free if you are within 60 feet of it, using normal grappling rules.  The arm has advantage on this check if you are within 20 feet of it."

I think it might be a bit of a trap, but I'd like to add to the points already said here: You could argue that the APA could be used with the "Dual Wielder"-feat combined with a Returning Weapon to make a trown weapon Battle Smith. I didn't calculate it all but makeing a third attack with the b-action could be helpful (combined with "Sharpshooter"). Then again you got the steel defender eating the bonus action most of the time.

Edit: You could also make a REALLY flavorful battle-mech style warforged/artillerist with it that wields the Arcane Canon and a Wand sheath in one hand and has a rocket fist as the other hand. - Wouldn't be mechanically bonkers but pretty fun to imagine.

Trap or not, I had fun with my Thri-kreen Artificer having two of these rocket fists. They are just so flavorfully satisfying.

In terms of the damage it does I think it's okay; it's basically a force dagger with better damage, which is pretty sweet. Personally I'd have expected it to be bludgeoning damage so force is a neat surprise.

Where the item gets interesting is the first bullet point "The prosthetic is a fully capable part of your body."

Now, do you interpret this to mean that the prosthetic is only fully capable when it's connected to your body, or do we assume it's still an arm while thrown? This is going to be one of those items where what you can do with it is going to be mostly down to the DM, but I can see some fun possibilities with it being a functional arm. Could you attempt to grab something with it, drop a bomb, grapple? If you detach it, can you still operate it and have it scuttle about like Thing from the Adams Family?

Regarding the comparison to the armblade, how about both? I would absolutely argue with my DM for the ability to stab someone with the armblade while rocket punching them, and rule of cool gives a good chance of winning that argument (especially as it wouldn't be all that powerful a combo).

I think if you take it exactly as written then, yeah, it's a little underwhelming. It's not terrible, and if it fits your theme then there really is no better alternative, but I think where it will shine is in being creative with it and hopefully your DM will be onboard as long as you're not going over the top with it.

The thought of being able to Dope Slap someone from up to sixty feet away is pretty amusing.  The cyberpunk transhumanist in me loves this thing to death; the D&D optimizer still can't help but look at it and see it as over-rarity'd for what it is.  Force damage is awesome, and the fact that it effectively becomes a natural weapon for the character is equally awesome, but 'Very Rare' is often the pinnacle of what a character can acquire for themselves.  A 1d8 weapon with no bonuses and the game's second-shortest throwing range feels just a little underwhelming for a Pinnacle Rarity Weapon.  Artificers get a pass on rarity so long as they burn an infusion slot on the thing, but speaking from experience here I can say that one does not want to have one of their infusions forcibly locked on "being fully functional."  My Battlesmith knows the Prosthetic Limb infusion, but she also has a regular/'real' prosthetic limb she normally uses instead as it's all too easy to disrupt infusions, and also sometimes you want to actually change those things out.

The DM for that artificer, as I mentioned about ten months ago, was (and presumably still is, since said artificer is nowhere near possession of an APA yet) super reticent to let the APA be an effectively cantrip-free Mage Hand.  I can see it, but having had considerable time to think about it, I don't know how much I agree anymore.  Especially if one limits the range of the APA's remote-hand-drone abilities to 20 feet rather than 30, Mage Hand still has an advantage.  Mage Hand also can't take damage that I'm fairly sure would still reflect back to you, RAW, since the APA is still technically part of you when it's flying around rocket punching/Mage Handing.  Admittedly, the thought of it not being able to fly save for its punch and instead just crawling around Thing-style is hilarious.  Not sure how effective it would be, especially for those artificers for which the APA is replacing their entire arm, but it's still hilarious.

It's still basically the coolest thing, and I still think that if your artificer is already down one arm there's no reason not to make that arm an APA whenever you can.  But it's definitely one of those things one has to chat with their DM about.  Though I will say, the Armorer is an interesting case for the APA.  Armorers already replace missing limbs, but there's a definite argument that an Armorer could use their Armor Modifications feature to integrate an APA into the armor directly as either a bracer(*) or a weapon.  Imagine an Infiltrator-model Armorer with the lightning launcher on one hand and an APA for their other hand to cover melee combat and add a bit of extra oomph after the first LL shot in a turn.  If your DM allows you to attack with Intelligence for the APA as well as the launcher (not RAW, but arguably within the spirit of the Power Armor feature), or if you pile on a Belt of Hill Giant Strength to render the point moot, could be a cool combo-play build.  The APA definitively beats out an armblade as one's backup melee stick, that's for sure.

Did I break this thing by adding it to my warforged artificer as a third arm, so I always had two free while wielding a shield?  My fantasy 20th-level artificer (as I don't even have a game where we can play artificer, let alone 20th level):

That third arm is a great party trick at the pub. BOM here has been known to cast shocking grasp onto this appendage, which just happens to be an arcane propulsion arm. Imagine the surprise on the boys' faces, when a charged arm flies across the room and grabs him by the man parts, with 5d8 damage. Talk about your ball buster! 

I also make tiny cannons on legs that ride around on a homonocolos as an attack drone...

Anyone who knows me, knows that I like ridiculous. 

Did I break this thing by adding it to my warforged artificer as a third arm, so I always had two free while wielding a shield?  My fantasy 20th-level artificer (as I don't even have a game where we can play artificer, let alone 20th level):

That third arm is a great party trick at the pub. BOM here has been known to cast shocking grasp onto this appendage, which just happens to be an arcane propulsion arm. Imagine the surprise on the boys' faces, when a charged arm flies across the room and grabs him by the man parts, with 5d8 damage. Talk about your ball buster! 

I also make tiny cannons on legs that ride around on a homonocolos as an attack drone...

Anyone who knows me, knows that I like ridiculous. 

It might be a trap, but it's a trap that lets you be Iron Man.

I know I'm very late to this, but I thought I'd point out that Tasha's added a Thrown Weapon Fighting style that adds +2 bonus damage to ranged attacks made with weapons that have the thrown property, such as the APA! There's also a new feat in Tasha's that lets you learn a fighting style so you can pick it without multiclassing, though I think proficiency with marital weapons is a prerequisite (not a problem if you're a Battlesmith).

Not sure how useful +2 damage will be by the time you pick up APA as an infusion at level 14, but it could be a great option if you stumble across one earlier. Plus the bonus to damage only applies when you make ranged attacks, so you'll still be dealing the normal d8+modifier if you just deck someone with it. But hey, the whole point of this weapon is being able to rocket punch people, right?

Quote from xmprz1342 >>

Quote from SadSquach >>

I know I'm very late to this, but I thought I'd point out that Tasha's added a Thrown Weapon Fighting style that adds +2 bonus damage to ranged attacks made with weapons that have the thrown property, such as the APA! There's also a new feat in Tasha's that lets you learn a fighting style so you can pick it without multiclassing, though I think proficiency with marital weapons is a prerequisite (not a problem if you're a Battlesmith).

Not sure how useful +2 damage will be by the time you pick up APA as an infusion at level 14, but it could be a great option if you stumble across one earlier. Plus the bonus to damage only applies when you make ranged attacks, so you'll still be dealing the normal d8+modifier if you just deck someone with it. But hey, the whole point of this weapon is being able to rocket punch people, right?

 if you combine with enchanced attack you can have a +4 to attak rolls with the APA, wich is a lot.

 Not sure what you mean with " enchanced attack" but if you mean the Infusion that gives you +1(+2) with the attacks of a weapon, sadly that doesn't work you can't infuse a thing twice.

Ok, since I don't want to make another thread re:APA, I'll just ask here. I don't mind if RAW shuts down all of these x)

On my sheet it shows as:
- a magic melee weapon
- can be thrown as 20/60 range
- has prof + str mod to hit
- deals 1d8 + str mod to hit

To clarify some stuff in my head:
1. Since the rocket punch is a Ranged Attack using a Melee Weapon, then this wouldn't work with Sharpshooter, since SS needs a Ranged Weapon?
2. Can this technically work with Booming Blade, at 20ft, since performing a to-hit with your weapon is the requirement of BB? considering DM-fiat approved(1sp weapon), because I'm confused how Spell Sniper is making it a 10ft range, while stating you target a creature 5ft from you.
3. On my turn, my initial action is to punch 20ft away, can my Extra attack be a Grapple or Shove while my fist is 20ft away, on my enemy's face?
4. Say Grapple works, and succeeds. My fists then "Immediately return and reattaches", it didn't say instantly, would that mean I made a grappling hook? >:^)  or how would you rule that?

Also, Charger feat seems like a waste, but it looks like I can kite enemies. Dash, move in any direction, punch from 20ft away, reposition with remaining movement. I can either deal piss poor damage, or keep knocking back enemies to 30ft distance. I'm just... trying to think of ways around this Propulsion Arm x)

Quote from Auvergh>>

1. Since the rocket punch is a Ranged Attack using a Melee Weapon, then this wouldn't work with Sharpshooter, since SS needs a Ranged Weapon?

It does work with Sharpshooter, but not the last bullet point (the -5 to attack for +10 damage option); the other bullet points only require ranged attacks (which is what throwing is), only the last one requires an actual ranged weapon, which unfortunately thrown melee weapons aren't.

2. Can this technically work with Booming Blade, at 20ft, since performing a to-hit with your weapon is the requirement of BB? considering DM-fiat approved(1sp weapon), because I'm confused how Spell Sniper is making it a 10ft range, while stating you target a creature 5ft from you.

Sadly, no, you can't use it with a "throw" attack. Booming Blade (and Green Flame Blade) both specifically require you to make a melee weapon attack (melee attack) against a target within 5 feet. Spell Sniper extends this to 10 because it lets you double the range of spells, and these two spells technically have a range of 5 feet (since they're not touch spells), though it's a bit of an edge case whether it should work for spells like these, since a DM could rule you're still limited by the weapon as you have to use it as part of the spell (so in theory the Spell Sniper increase might only work with reach or on a Bugbear or similar).

3. On my turn, my initial action is to punch 20ft away, can my Extra attack be a Grapple or Shove while my fist is 20ft away, on my enemy's face?

I don't think there's a way to do that in RAW, as you resolve one attack before moving onto the next (so you arm is back by that point, since it's immediate). It's absolutely something a DM should rule you can do because it's fun, and not enough people grapple so more grappling should always be allowed IMO.

4. Say Grapple works, and succeeds. My fists then "Immediately return and reattaches", it didn't say instantly, would that mean I made a grappling hook? >:^)  or how would you rule that?

Usually when a rule says "immediately" they mean something happens in an instant, so your fist comes back so fast it doesn't interrupt anything. Again though this is absolutely something a DM should let you have fun with because if a DM has a character with a rocket arm in their campaign they are honour bound to allow fun stuff with it or lose kudos points for all eternity.

I think it's a fun item; not quite as awesome as it might sound at first glance, but with a DM that's happy to give you some leeway with it it should be a lot of fun. It's probably not going to be a main weapon, but you should 100% come up with ideas for cool ways to use it, don't worry about the rules, and just run some of it by your DM in advance to see what types of things they'd be okay with.

Whelp, at least there's SS to consider atm. 60ft punch doesn't sound so bad to me >:^)

Thanks for the feedback man o/

Yes yes, I know - I'm breaking my own rules and bumping my three year old dead thread. Necromancy bad bleh.  Sorry.

But! I do so because I finally have some actual playtesting experience behind an APA now to report on, so nyah!

Sadly, my lovely artificer's campaign ended before she accumulated the levels required to gain an APA, but my ranger in a Cyberpunk-inspired game was able to use one for several sessions before Time Hijinks snatched it away from her.  The DM was kind enough to let me bend the rules a bit and use my Dexterity mod for its attacks, as well. The APA was directly competing with a +1 longbow I had during this interstice as well, and the character in question does have Sharpshooter despite my general disdain for the feat.  Story Reasons.

First note: now that prosthetic limbs have changed and no longer require attunement, the APA is back to being an attunement tax.  Unless you carry around a spare basic prosthetic (which isn't an awful idea, the prosthetic can be damaged independent of the character), once you attune to an APA you can't unattune it without losing a limb. This is a distinct drawback in loot-heavy games.

Second note: being able to switch between melee and ranged combat seamlessly is just as handy as it sounds.  When enemies rushed Taiko, she could defend herself with her prosthetic force claws, stand her ground, and keep up the pressure without having to retreat or waste a turn swapping weapons. That was VERY important in her last fight with the APA, which was very tight and required me to borh tank for the casters and deal as much damage as I could while I did.  1DD rules makes swapping weapons easier, yeah, but it's still not as easy as using a natural  weapon. 

Third note: it's just ******* cool.  Could I do more damage with my longbow?  Yes.  Did ot matter when I was slashing wounds in my foes with metal claws burning with arcane runes or stabbing them from afar with brutal flying-spearhand strikes?  Nuh.  It was awesome, and allowed Taiko a glimpse of an entirely new fighting style.  One she's admittedly not well set up for, given her previous focus on Archery and Sharpshooter, but it was just freaking fun and I already miss it. An argument can be made, after all, that Dueling applies to the propulsion strikes from the APA.

Fourth note: it doesn't actually interfere with your other weapons.  When the boss we were fighting burrowed away to harangue the casters, Taiko's force claws meant she got a meaningful opportunity attack no matter what she was holding, and she could switch to her longbow almost as seamlessly as switching ranges with her claws.  When I needed to start taking Power Shots to pile on the damage, I could do so while still keeping my AoO weapon ready to "hand" (tee hee hee) and not losing any time or steam. The APA honestly felt a lot like Martial Arts off the monk - you could use your weapons freely, but if the situation called for it you could switch to unarmed blows freely or mix them in with normal attacks.

Overall?  The Arcane Propulsion Arm is one of the coolest magic items I've ever used.  Whether or not it's a trap by optimancer standards is immaterial; I had such a hoot using it I'm considering asking for it back as the Story Boon we all earned last night.  The thing is so evocative, it practically begs for Cool Story Moments and flashy combat descriptions. The item gets a five-fingerstar review from me and a Highly Recommend for anyone that has a chance to try it.  You won't be disappointed.