+1 Life Vine Hide Armor

+1 Life Vine Hide Armor
This armor is woven with an intricate lattice of living vines that form a symbiotic relationship with the wearer.  This armor is very ancient.  The back of this armor has a mountain and a cross design weaved into it.
Property:  Gain a +1 to AC
 Once a day, as a reaction when an enemy scores a critical hit against you, you can roll a hit dice and heal for the amount rolled +1.
Temperate:  The wearer feels no effects of cold temperatures as low as 0 or as warm as 120 degrees.
Secret:  Due to the symbiotic nature of the armor, it can’t easily be taken off, and if removed, it loses its enchantment.