Teresa of Avila's Bottle of Holy Water

Origin
Before Teresa Canchex de Cepeda Y Ahumada (1515 - 1582) became a prominent Spanish mystic, Roman Catholic saint and theologian she was a wandering Carmelite Nun who offered her services as a nun to those in need. Among the many acts of charity she would baptism people into the faith. No matter where she went she had a simple bottle of blessed, holy water which never seemed to be empty. One day when she was baptizing a young man a wild dog attacked them. Dropping the bottle it spilled and when the mongrel attacked it seemed to bounce off nothing, unable to get at them the dog soon gave up and left.

Effects
Creates an invisible shield that could only be removed by whoever uses it by using foot to break the line. Also the bottle never seems to be empty.