Geas

Geas is a magic spell used to seal an oath or to force someone to do the caster's bidding. Should the target of a geas spell fail in their quest or break their oath, they will suffer dire consequences, like grievous pain and/or death.

The geas spell cannot be dispelled by any conventional means like Dispel Magic or Remove Curse. The only way to remove geas in the first game is to use the Geas Removal Scroll from Jalantha Mistmyr.

Availability
The Geas spell is unavailable in the both games, meaning that no one can learn it or cast it. However, at least two characters who serve an important role in the plot are scripted to be under the effects of a geas:
 * Lothander in Baldur's Gate (game) and Baldur's Gate: Enhanced Edition
 * Yoshimo in Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition