Arm of convergence (prosthetic)

Spiral’s Prosthetic: The Arm of Convergence

Wondrous item (prosthetic), legendary  (Forcefully opens up a attunement slot for itself)

Appearance:
This prosthetic arm is made of dark silver metal, smooth yet veined with faint blue, coral-like etchings. The arm is segmented into eight hovering disc-like joints, which rotate and shift freely when the arm is active. A hum of arcane energy and flowing water can always be faintly heard when nearby. When idle, the discs silently lock back into their natural arm-like form. The fingertips glow faintly with crystalline energy, and the entire structure moves as if alive—fluid, natural, almost breathing.

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Base Abilities

🜁 Convergence Discs (3/short rest)

The arm can launch up to 3 discs as a bonus action or action. Each disc deals 2d6 + int modifier force damage and can travel up to 60 ft in a straight line. You can curve their trajectory slightly. You may target separate enemies. The attack role is the same as your normal weapon attack

• Return: After striking, the discs arc through the air and reassemble on your arm, returning at the start of your next turn.

• Defensive Use: As a reaction, you may send a disc to intercept a ranged attack (add +1 to AC vs. that attack).

🜃 Unbound Flow (Passive)

The arm grants +10 ft movement speed and allows you to ignore difficult terrain once per round. When sprinting or dashing, faint liquid-like trails of energy follow your motion.

🜂 Surge Pulse (1/long rest)

As an action, you can channel the energy of the arm, causing the discs to orbit rapidly. Choose one when having a disc dissasembled:

• Nova Pulse: All creatures within 15 feet must succeed on a Dex save (DC = 8 + Prof + Cha) or take 4d10 force damage and be pushed 10 ft away.

• Siphon Storm: The discs spin outward in a spiral pattern, absorbing ambient magic. Any active spell effect (of 4th level or lower) within 30 ft must make a dispel check (as per dispel magic), or be suppressed for 1 minute.

🜄 Integrated Weapon Form (Bonus Action)

The arm can shift seamlessly into one of three melee weapon forms:

• Whip-form: Reach +10 ft. Counts as a magical whip.

• Blade-form: +1 magical scimitar with finesse.

• Knuckle-form: +1 magical unarmed strikes, allowing a second unarmed strike as a bonus action if you hit.
  
  

  Rocket Overdrive

  (1/Long Rest) As an action, you launch the gauntlet at a creature you can see within 80 feet. Make a melee weapon attack using Strength.

  On a hit, the target takes 2d10 bludgeoning damage. The serpent core then detonates, forcing each creature within 15 feet of the target to make a DC 16 Constitution saving throw, taking 6d6 thunder damage on a failed save, or half on a success. Creatures that fail are pushed 15 feet and knocked prone.

  Creatures within 5 feet of you when the gauntlet launches must succeed on a DC 14 Dexterity saving throw or take 2d6 thunder damage from the backblast.

  The gauntlet immediately returns and reattaches after the attack. On a miss, the explosion still occurs at the impact point.

   

It’s up to you to decide whether a character has proficiency with a firearm. Characters in most D&D worlds wouldn’t have such proficiency. During their downtime, characters can use the training rules in the Player’s Handbook to acquire proficiency, assuming that they have enough ammunition to keep the weapons working while mastering their use.

Notes: it forcefully opens an attunement slot for itself if every slot is being used, Range, Two-Handed, Ammunition (Firearms), Reload, Sap