Hellish Rebuke

Level: 1

Casting Time: 1 reaction, which you take in response to being damaged by a creature within 60 feet of you that you can see

Range: 60 feet

Duration: Instantaneous

You point your finger, and the creature that damaged you is momentarily surrounded by hellish flames. The creature must make a Dexterity saving throw. It takes 2d10 fire damage on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d10 for each slot level above 1st.

Source: PHB, page 250. Available in the SRD.