Level 1 Evocation (Warlock)
The creature that damaged you is momentarily surrounded by green flames. It makes a Dexterity saving throw, taking 2d10 Fire damage on a failed save or half as much damage on a successful one.
Using a Higher-Level Spell Slot. The damage increases by 1d10 for each spell slot level above 1.
Damage by slot level: 1: 2d10, 2: 3d10, 3: 4d10, 4: 5d10, 5: 6d10, 6: 7d10, 7: 8d10, 8: 9d10, 9: 10d10