Divine Smite

When you hit a creature with a melee weapon
attack, you can expend one spell slot to deal
radiant damage to the target, in addition to the
weapon's damage. The extra damage is 2d8 for a
1st-level spell slot, plus 1d8 for each spell level
higher than 1st, to a maximum of 5d8. The
damage increases by 1d8 if the target is an
undead or a fiend, to a maximum of 6d8.