Armor of the dragon

 Advantage on str/con roll/check twice per long rest 

Allows the use of a breath weapon 3 times per long rest as a bonus action, apply breath weapon stats

When character reaches 0HP player can choose to do death saves or activate the armor becoming an invulnerable Lv20 barbarian player dies on an encounter end and can't be revived

 

This armor consists of a coat and leggings (and perhaps a separate skirt) of leather covered with overlapping pieces of metal, much like the scales of a fish. The suit includes gauntlets.

Notes: Bonus: Armor Class, Stealth Disadvantage