Anti-Magic Appendage

This prosthetic appendage is commonly made with polished metals, such as copper or silver and is inscribed with runes along the point that attaches to the body. To attune to this item, you must attach it to your arm at the wrist, elbow or shoulder, at which point the prosthetic magically forms a copy of the appendage it's replacing.

While attached, the prosthetic provides these benefits:

• The prosthetic is a fully capable part of your body.
• You can take an action to remove the prosthetic, and it removes itself if your attunement to it ends. It can't be removed against your will.
•  When you are targeted by a spell of third level or lower, or caught in the area of effect from a spell of the same levels, you can expend a reaction to cast Counterspell from the arm. You cannot use this feature again until you complete a long rest. 

Notes: Requires attunement by a creature missing a hand or arm