Item: Amulet of Endurance

I was thinking about an item that plays with the exhaustion mechanic, and the first iteration was pretty much just the Potion of Vitality, which isn't anything new or interesting. The second iteration prevent levels 5-6 of exhaustion, which felt overpowered. Exhaustion is a cost that you must pay if you don't manage it (and this is most pronounced with the Berserker Barbarian). It also granted advantage on Constitution saving throws against exhaustion, but I realized that some exhaustion effects don't offer a save.