S/Self/1 round

You have resistance to the triggering damage type until the start of your next turn (acid, cold, fire, lightning, or thunder). Also, the first time you hit with a melee attack on your next turn, the target takes an extra 1d6 damage of the triggering type, and the spell ends.

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.