Reinforced (3.5e Equipment)
From D&D Wiki
Reinforced: Reinforcement is a powerful enhancement for shields or armor allowing its wielder and her equipment(for a short time at least) to take on extremely resilient properties. Upon will of the wearer the enchanted item transforms itself, its wearer, and the rest of her equipment in to living adamantium. All equipment is adamantium for the purposes of bypassing or applying DR, and the user is treated in all ways as a construct for the duration. This also grants a natural armor bonus of +15, 20 resistance Fire, 20 resistance Cold, And Electricity immunity.
This state last for one round per activation. To use the Reinforced ability the user must make a concentration check (DC 10 + the number of rounds this ability has already been used today). This is a swift action and checks may be made consecutively each round to prevent the effect from fading.
Moderate transmutation;CL 18; Craft Magic Arms and Armor; Market Price: +5 bonus