Sinew Bow

Requires attunement.
When you attune to this arrow, it becomes a tattoo on your inner forearm. When you activate it, your maximum hit points are reduced by 2d6 as your radius and ulna separate from
your elbow - a strand of sinew connecting them - forming a magical longbow at your wrist. A bone spur in your arm can be drawn into a bone arrow, which deals an extra 2 damage. You can retract the bow back into your arm at will.