Divine Smite

Level & School 1st-level evocation
Casting Time Bonus action, which you take immediately after hitting a target with a melee weapon or an unarmed strike
Range Self
Components V
Duration Instantaneous
Classes Paladin

The target takes an extra 2d8 Radiant damage from the attack. The damage increases by 1d8 if the target is a Fiend or an Undead.

Using a Higher-Level Spell Slot. The damage increases by 1d8 for each spell slot level above 1.