Tiamat's Wrath

As a reaction when you take acid, cold, fire, lightning or poison damage, you can invoke Tiamat's protection. You gain resistance to the damage type of the triggering effect until the start of your next turn, and as part of casting this spell, you exhale a breath weapon of that same type in a 15-foot cone. Creatures in the cone must make a Dexterity saving throw, taking 2d6 damage on a failed save or half as much on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the extra damage increases by 1d6 for each slot level above 1st.