You add your Constitution modifier to your Armour Class in addition to your Dexterity modifier when not wearing armour.
Description
Your body is as resilient as any armour. While not wearing armour, you add your Constitution Modifier to your 
Armour Class. Wearing Heavy Armour impedes your Rage.
Progression
- Learns at level 1: Barbarian
Notes
This passive is disabled when Mage Armour is applied.
This passive does not stack with Unarmoured Defence (Monk) instead only the larger modifier of the two is applied