While Vincal used most of her magic offensively, she had a few tricks when it came to defense. The intricate, overlapping plates of her armor looked strong and sturdy, convincing most observers that harming her with a strike would be a difficult task. The key to her armor, however, was not its thickness or masterfully crafted design; it was how it manipulated her spells to keep her alive. Each plate is enchanted to tune them to the soul of the user.
You can change the armor to better fit your characters or use, but here are some stats for it for a d20 game: Soul Spinner is a masterwork set of medium armor made up overlapping plates. It gives the wearer a +6 bonus to AC with a max dex bonus of +2. It has an armor check penalty of -3, a 20% spell failure chance, and a speed of 20 feet. It weighs 20 pounds.
Soul Spinner allows the user to convert unused spells into a magical field that absorbs damage. As a free action, the wearer can react to an attack against her. By infusing the unused spell into the armor, the armor can reduce the damage dealt equal to 5 times the spell level.
For example, if she uses a 3rd level spell, she reduces the incoming damage by 15. If she uses an 8th level spell, she reduces the damage by 40. It only absorbs damage for one attack. If she uses a 4th level spell to absorb 20 damage after being dealt 17, the remaining absorption is not used.
This ability is not usable when she is unaware of an attack. While the action is nearly instantaneous, she must make the decision herself. If struck by an unexpected source, the damage is already dealt.
This ability reduces physical (falling, slashing, fire, etc.) and magical (magical fire/acid/ice/etc., infernal magic, spell-like abilities, etc.) types of damage. It cannot stop non-physical damage or magical damage that does not have a physical manifestation (psychic, sonic, etc.)
She can only do it once per round, or if she’s not in initiative, once per source of damage. Thus, she cannot use 3 2nd level spells to try and absorb 15 damage from a fall.