Desecrated Ground

Some cemeteries and catacombs are imbued with the unseen traces of ancient evil. An area of desecrated ground can be any size, and a detect evil and good spell cast within range reveals its presence.
Undead standing on desecrated ground have advantage on all saving throws.
A vial of Holy Water purifies a 10-foot-square area of desecrated ground when sprinkled on it, and a hallow spell purifies desecrated ground within its area.