Adamantine Plate of Donning and Doffing

This suit of armor is reinforced with adamantine, one of the hardest substances in existence. While you're wearing it, any critical hit against you becomes a normal hit.
The armor can be expanded or retracted from a necklace as a bonus action. While expanded any exhaustion checks due to extreme heat or cold can be made with advantage
Note a separate magical necklace or amulet cannot be worn at the same time as the armor.

Plate consists of shaped, interlocking metal plates to cover the entire body. A suit of plate includes gauntlets, heavy leather boots, a visored helmet, and thick layers of padding underneath the armor. Buckles and straps distribute the weight over the body.

Notes: Immunity: Critical Hits, Bonus: Armor Class, Combat, Warding, Str. 15 Required, Stealth Disadvantage