geas

noun

1. A (generally magical) vow, obligation or injunction placed upon someone to do or not do something, which typically brings harm if violated and blessings if obeyed.

   “It can send us where it will with a task laid upon us—a geas, if you like.”

   “Galaad stood up again and turned to Mrs. Whitaker. 'Gracious lady, keeper of the Holy of Holies, let me now depart this place with the Blessed Chalice, that my journeyings may be ended and my geas fulfilled.'”

   “The geas is the last effective enchantment we shall consider. A geas is a restriction or compulsion laid upon a person by a druid or a bard. To break a geas is to forfeit one's share of luck and possibly one's life.[…]Geasa are not curses, but recognitions of individual needs given to protect and help an individual succeed at life.”

   “A geas is a powerful binding spell that binds its subject to a particular task or restriction. Frequently in Irish legends, the playing out of a geas laid upon a hero reminds one of the playing out of fate in the Greek tragedies.”

   “The Sorcerer Royal's servants had formerly been bound by a geas against disclosure of any detail of his household affairs, breach of which was visited by the most terrible revenge.”

2. A mystical compulsion.

   “The memory came upon him like a geas, overwhelming his revulsion, numbing his heart.”

   “A geas is your own personal haunting by yourself! […] Kassandra, a Greek prophetess who always envisioned dreadful happenings, had a geas on her. She might have wanted to be a queen or a housewife, a warrior or a merchant, but she wasn't (even though a geas won't interfere in any of your pursuits). She became legendary for the geas that propelled her to prophesy dreadful happenings.”