Adamantine Armor

Armor Type: Any Medium or Heavy Armor, but not Hide Armor

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.

Classes

Artificer
Barbarian
Bard
Cleric
Druid
Fighter
Monk
Paladin
Ranger
Rogue
Sorcerer
Warlock
Wizard

Magic Armor

Common
Uncommon
Rare
Very Rare
Legendary

Armor Types

Light Armor 
Medium Armor 
Heavy Armor 
Shields