Sentence:  A <WSD>geas</WSD> is your own personal haunting "by yourself!"...Kassandra, a Greek prophetess who always envisioned dreadful happenings, had a <WSD>geas</WSD> 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 <WSD>geas</WSD> won't interfere in any of your pursuits). She became legendary for the <WSD>geas</WSD> that propelled her to prophesy dreadful happenings. 
Meaning of the word marked with <WSD> tags:  A mystical compulsion.