This spell altered a spherical area 10 ft (3.1 m) in diameter so that, while the caster remained within the area, he or she gained some magical benefits for guarding that area. The spell lasted an hour for every level of the priest, or if the priest left the area, whichever came first. Benefits included:
- Enhanced sight, such that the caster could see in total (normal) darkness and see invisible creatures. The range of sight was 60 ft (18.3 m) unless blocked by solid objects.
- Freedom from hunger, thirst, or fatigue. The caster required no food, water, or sleep for the duration of the spell. Note the idea was to remain vigilant, so no sleep was possible, i.e., no new spells could be learned.
- Slow regeneration. The caster's health improved slightly with every passing hour.
- Complete immunity to fear, magical or otherwise, and sleep and charm spells.
After the spell expired, the caster had to rest about a sixth of the time spent in the vigil and felt sluggish until this recovery period was over.
In addition to verbal and somatic components, the priest had to spend 10 minutes writing runes and symbols in a 10 ft (3.1 m) circle. The ink used was specially made with powdered emerald, at least 1,000 gp worth.