The ring has 1d6+4 charges for the following property.
(To reflect the horror of Ravenloft, this ring doesn't regain it's charges, however if you prefer it could regain 1 charge each week.)
Vengeance. When you hit an undead creature with a melee weapon attack, you can expend one charge to cause the attack to deal 7d6 radiant damage to the target.
Lyle Focault loved his wife, Marie, and their four children beyond anything else in this dread domain they called home. It was odd luck that brought him home after the sun had dipped behind the mountains and fickle fate that had the vampire, Donal Remming, find him and curse him with undeath merely a mile from the his beloved home. When he rose from the shallow grave that night the vampire Remming had left him in, Lyle's only instinct was to go to his dearest family. But as he came to the threshold of his home, one that he had built with his own hand and the family it protected from the night, the thirst overtook him. As the rays of the sun rose the next morning, his devotion to his beautiful family was the only thing that kept the curse of undeath at bay as the purifying light destroyed the undeath that trapped him. Though he wept, he did not scream, for he didn't want his family to know of his dark fate. However, as they began their chores that morning, his bride found her husband's wedding ring on their doorstep. Somehow she knew, that one day they would be together again.