Armor of inner strength

This armor is bound to its wearer and its hardness grows just like the inner strength of its wearer. The AC of the armor is 14 + the proficiency bonus of its wearer. The armor cannot be taken off. 

This armor consists of a fitted metal chest piece worn with supple leather. Although it leaves the legs and arms relatively unprotected, this armor provides good protection for the wearer's vital organs while leaving the wearer relatively unencumbered.

Notes: Bonus: Armor Class