Credit: Uncredited fanart for Valkyrie Cain's ring from Skulduggery

Wondrous item, very rare

This ring converts your life energy into a shield around you. As an action, you can use this ring to take the exact amount of damage necessary to reduce your HP to 1. You gain temporary hit points equal to double the amount of damage taken. The effect lasts for 1 minute, during which you cannot be affected by any healing. At the end of the duration, you lose all remaining temporary hit points. The effect ends if you are knocked unconscious or killed.