Desecrated Ground

Wilderness Hazard

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.

Source: Dungeon Master’s Guide p. 110