You conjure a magical suit of glass armor over your existing armor and apparel for the duration. The glass armor appears in any color and style you choose. If you are wearing heavy armor, you have disadvantage on attack rolls as the bulk of the glass armor on top of the heavy armor limits your range of movement. Until this spell ends, your AC increases by 3 and you have advantage on saving throws against spells and effects that would alter your form.    When you cast this spell, the armor has a number of charges equal to your spellcasting ability modifier. Whenever you take cold, fire, lightning, or poison damage, you can use your reaction to expend a charge and reduce that damage to zero. The spell ends early if all charges are expended.    If you take thunder damage while wearing this glass armor, you must make a Constitution saving throw as if you were concentrating on a spell. On a failed save, this spell ends, as the glass armor shatters from the thunder damage.