Ceremonial Helm of Agris

Wondrous item, uncommon (requires attunement by a spellcaster)

This ceremonial helmet is exquisitely designed with an iron and bronze structure layered with pure gold leaf. The design belongs to Celtic Gaul and is used primarily for ritual and status purposes, never for war. While you are wearing the Agris Helm, you may select one spell from your spell list and cast it as a ritual even if it is not a ritual spell. The spell you choose may not deal damage to any creature. Once you have done this, you cannot do it again until you finish a long rest.