A geis or geas (pl. geasa) is an idiosyncratic taboo, whether of obligation or prohibition, similar to being under a vow or curse, yet the observance of which can also bring power and blessings. It is also used to mean specifically a spell prohibiting some action. Geasa are common in Irish and Scottish folklore and mythology, as well as in modern English-language fantasy fiction. - Wikipedia
某种为保持力量所需的神圣誓言，中文无对应词汇（禁制？誓约？）。风格上类似DND五版的圣武士誓言。