Geas

Mandates an individual perform some task specified by the caster, or weaken or die.

Original D&D[]

Debuted in Men & Magic, for the magic-user. Dragon Magazine #12 put this spell on the Illusionist list as well, at a lower level.

Spells
OD&D Spell
Level 6 Spell
2 more
Magic-User Spell
Illusionist Spell

Spell Level 6 (magic-user) or 5 (illusionist)
Range 3"
Duration Until completion

Forces the recipient to perform some task desired by the caster. Any attempt to forestall the task causes the subject to become weak, and ignoring the task completely brings death.