Divine smite

when you hit 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.