Helm of the Skeleton (Patreon)

Wondrous item, uncommon (requires attunement)

While wearing this helmet, any skeleton or skeletal creature that has a challenge rating of 1 or lower is indifferent towards you unless commanded or until either you or your companions harm it. In addition, any damage you deal to an undead creature counts as magical and ignores its Undead Fortitude trait, if it has it; you also only require half as much food and drink as normal. An undead creature wearing this helmet gains a +1 bonus to AC, even if it's not attuned to it.

Curse. This helmet is cursed, and becoming attuned to it extends the curse to you. While cursed, your skin becomes leathery and gaunt against your frame. If you die while cursed and aren't returned to life (such as by the revivify spell), you're transformed into a zombie or skeleton (GM's discretion) after 24 hours. This transformation can be delayed by certain magic, such as the gentle repose spell, until that effect ends.

A mangled helm atop his skull,

t'would look like any other.

But see within its iron hull,

a curse designed to smother.