A derivative of the Fire Shield
spell (both count as the same spell). An icy mist wreathe your body for the duration, shedding bright blue light in a 10-foot radius and dim light for an additional 10 feet. You can end the spell early by using an action to dismiss it.
The chilly mist provides you with an icy shield (or a fire shield, as it's alternative suggests). The chill shield grants you resistance to fire damage (and the fire shield grants you resistance to cold damage).
In addition, whenever a creature within 5 feet of you hits you with a melee attack, the shield erupts with a blast of cold and the attacker takes 2d8 cold damage (or 2d8 fire damage from a warn shield).
a crystal of sodium acetate or a piece of ice
Protego di Frigus
Verbal Component (Alternative):
Mystic powers that I now wield, summon forth a chilling shield.