Arcane Propulsion Arm is basically a thrown weapon with the returning property. An artificer could make a +1 yklwa, and it'd be stronger than an Arcane Propulsion Arm, though it'd have half the range. You can't be unequipped, but the same's true of an arm blade or anything owned by an Eldritch Knight; the same is true for Hexblade's weapon.

It just seems REALLY high for it, when the only thing that's really standout about it is the force damage. Can someone explain how power vs rarity is calculated, and justify this?

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    \$\begingroup\$ Hey, welcome to Role-playing Games! Have you seen our tour? This looks like an interesting question, I hope you get a good answer, Or a few! Welcome again, and have fun! \$\endgroup\$
    – Chemus
    Commented Jan 23, 2022 at 7:04
  • \$\begingroup\$ An yklwa is not a prosthetic appendage, so I'm not sure that's a valid comparison. The comparison should be to other prosthetics. \$\endgroup\$ Commented Jan 23, 2022 at 10:21
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    \$\begingroup\$ Related: Is item rarity really tied to how powerful it is? \$\endgroup\$
    – Mołot
    Commented Jan 23, 2022 at 11:32
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    \$\begingroup\$ @ThomasMarkov this is a question I asked, so I'd rather abstain from voting. I wouldn't be objective. \$\endgroup\$
    – Mołot
    Commented Jan 23, 2022 at 12:52
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    \$\begingroup\$ @ThomasMarkov No, it’s not a duplicate. An answer of “being very rare doesn’t necessarily mean that the arcane propulsion arm is supposed to be powerful” would be incomplete, and that’s all the answer that the linked question could provide. A proper answer to this question would have to be something like “being very rare doesn’t necessarily mean that the arcane propulsion arm is supposed to be powerful, and indeed it isn’t,” or “but in this case, it actually is,” and then of course back up those claims. \$\endgroup\$
    – KRyan
    Commented Jan 23, 2022 at 13:46

2 Answers 2


Magic Items are secondary to the design of 5e

In a tweet, Chris Perkins said

If your 5E characters have no magic items, the game would still be balanced. Magic items are pure candy.

The designers created D&D 5e to be able to function without assuming characters have magic items, and magic items do not appear in the Player's Handbook (Though some of them appear in the Basic Rules)

Thus, magic items are typically not as carefully balanced as other aspects of the game, they are an optional rule.

Magic Item Power Level is Largely Inconsistent

There is no guarantee that a magic item's rarity will give you any indication of how powerful it is, and items within the same rarity are not necessarily balanced or consistent with each other. Consider the Staff of the Python, an Uncommon magic item that is considered to be incredibly overpowered:

You can use an action to speak this staff's Command word and throw the staff on the ground within 10 feet of you. The staff becomes a giant Constrictor Snake (see the Monster Manual for statistics) under your control and acts on its own Initiative count. By using a Bonus Action to speak the Command word again, you return the staff to its normal form in a space formerly occupied by the snake.

And, the more important section:

If the snake is reduced to 0 Hit Points, it dies and reverts to its staff form. The staff then shatters and is destroyed. If the snake reverts to staff form before losing all its Hit Points, it regains all of them.

This means if you use your Bonus Action to recall the Snake, you can infinitely replenish it's hit points, of which it has 60.

Compare the potential utility of this item with the Cloak of Elvenkind, which makes you better at stealth, and consider these two items are of the same rarity.

All this being said, there is a good case to be made that the Arcane Propulsion Arm is aptly placed, and consistent with other options in the Very Rare tier.

The Arcane Propulsion Arm is essentially replicating a 7th level spell

The Arcane Propulsion arm acts as a prosthesis for a creature missing a limb, it improves upon the Regenerate spell, which states

The target’s severed body members (fingers, legs, tails, and so on), if any, are restored after 2 minutes. If you have the severed part and hold it to the stump, the spell instantaneously causes the limb to knit to the stump.

This makes the Arcane Propulsion Arm consistant with other magic items in it's tier, namely, the Amulet of the Planes,

While wearing this amulet, you can use an action to name a location that you are familiar with on another plane of existence. Then make a DC 15 Intelligence check. On a successful check, you cast the plane shift spell. On a failure, you and each creature and object within 15 feet of you travel to a random destination. Roll a d100. On a 1–60, you travel to a random location on the plane you named. On a 61–100, you travel to a randomly determined plane of existence.

This item is also Very Rare and replicates a 7th level spell. Also consider the Spell Scroll chart, and note the rarity of a 7th level scroll.

Spell Level Rarity Save DC Attack Bonus
Cantrip Common 13 +5
1st Common 13 +5
2nd Uncommon 13 +5
3rd Uncommon 15 +7
4th Rare 15 +7
5th Rare 17 +9
6th Very rare 17 +9
7th Very rare 18 +10
8th Very rare 18 +10
9th Legendary 19 +11

At least in this case, an item that can essentially cast or emulate a 7th level spell should be considered Very Rare.

This being said, the Prosthetic Limb from Tasha's Cauldron of Everything is considered Common, another point in the favor of the rules and rankings of magic items being inconsistent.

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    \$\begingroup\$ I have never really considered that staff overpowered, but items that grant flight are my favourite example and your point is entirely valid. Rarity in magic items terms is an absolute joke. \$\endgroup\$
    – SeriousBri
    Commented Jan 23, 2022 at 16:26
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    \$\begingroup\$ This statement is not true and magic items do not appear in official sources until the Dungeon Master's Guide They (a small number of them) appeared in the DM basic rules that were available for free (and which were combined with Player Basic Rules in 2018) and they appeared in the Starter Set. There were also magic items appearing in each published adventure, some of which predated the release of the DMG. \$\endgroup\$ Commented Jan 23, 2022 at 17:29
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    \$\begingroup\$ I don't think re-attaching severed limbs is really the primary point of Regenerate. The big heal burst plus becoming functionally unkillable by regenerating actual HP at the start of each turn is what makes it worth a 7th level slot... This strikes me as sort of like saying an item that can light torches at range is replicating fireball. \$\endgroup\$ Commented Jan 24, 2022 at 5:27
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    \$\begingroup\$ I don't think there even ARE any rules about severing limbs in the game? Nor are there rules for consequences of missing limbs. While Regenerate can fix them, losing them is entirely houserule territory. \$\endgroup\$
    – Erik
    Commented Jan 24, 2022 at 10:07
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    \$\begingroup\$ @Erik The Dungeon Master's Guide has optional rules for injuries that comes with a Lingering Injuries Table that you roll on for your injury, and two of the possible results involve loss of arm or leg, as well as the mechanical impediments associated with such injuries. \$\endgroup\$ Commented Jan 24, 2022 at 14:55

The simple answer is that rarity and power level are only tangentially linked.

Powerful magic items are comparatively rarer than less powerful magic items of the same type, simply due to the crafters capable of creating them being more rare, but that doesn't mean less powerful magic items are equally common when compared to each other across types. Some are simply crafted less frequently, making them rarer.

Gauging power level by rarity is an exercise in futility, much like sorting power level by weight.

  • \$\begingroup\$ that may be, but the DMG explicitly conflates the two, so there should be at least some kind of correlation. what you're describing is all in game flavor, while my question is more for the mechanics based around the line in the DMG that says "Rarity provides a rough measure of an item's power relative to other magic items." \$\endgroup\$ Commented Jan 25, 2022 at 17:28

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