A geas is a compulsion placed upon someone through supernatural means. The Tradition, the Code, fate-weaving, and cursing can all place a geas upon someone, but there are means pulling from raw poioumenon that may evoke it:

1. Eliciting a vow. If the right sort of vow is made by someone, a geas will naturally befall them.
2. Gaining a narrative upper hand. If the story dictates a geas, one may invoke it if one is aware of the narrative.
3. Bonds of powerful emotion can create geases. Love is the most common. If one has sworn love for another, then that other has a power over you and may instill a geas by making a command.