Necklace of Strangulation

This beautiful necklace appears to be a magical item such as a necklace of fireballs or a pendant of the occult. When invested, it magically locks in place, suspiciously tightly, and fuses to you. When you enter a situation of extreme stress (as determined by the GM), the necklace tightens around your neck, suffocating you and dealing 30[bludgeoning] damage to you at the end of each of your turns. Once per round, you can spend a single action to attempt a DC 34 athletics check or DC 34 fortitude save; success means you don't take the damage on your current turn, but you continue suffocating. The necklace loosens after you've been dead for a month.