Cap of Thick Skulls

Wondrous item, uncommon (requires attunement)

This hard iron headgear is shaped like a skull and squeezes tightly to your head. While wearing this helmet, when you make an unarmed attack you may follow up with a headbutt as part of the same attack. The target must make a DC 15 Constitution saving throw or be stunned until the end of their next turn. If you headbutt again before taking a short rest, you must also roll to be stunned.