Oathbow

(Requires attunement)
When attacking, you can, say, "Swift death to you
who have wronged me." The target becomes your
sworn enemy until it dies or until dawn seven days later. You can have only one such sworn enemy at
a time. When your sworn enemy dies, you can
choose a new one after the next dawn. You have advantage on attacks against them. Your target
gains no benefit from cover, save for full cover. If
the attack hits, your sworn enemy takes an extra
3d6 piercing damage.