SPELL_POISON

Usage       : cast poison <victim | food | drink>
Accumulative: Yes on persons.
Duration    : 2 ticks per level, permanent on food and drinks.
Level       : Level 8 cleric
Damage Type : General
Mana Usage  : 10

Casting poison on a piece of food or a drink container will poison it.
Consuming poisoned food or drinks will poison the person eating or
drinking.

If poison is cast on a player or mob, they are allowed a saving throw vs.
poison to avoid the effects. A person who is poisoned will suffer 2 points
of damage every tick, and regenerate hit points, mana and movement more
slowly. Sleeping may help to reduce the effects of poison.

See also:  "REMOVE POISON"