Poison Field

One of the spells to create a magical field is Poison Field.

Spell Description
Poison Field is very similar to the Poison spell.The spell creates a field that will poison the first creature stepping on it, even the caster's party. However, it shares the same weakness as Poison, as the poisoned foe can still attack and endanger the caster. While originally the field was permanent, later incarnations of the spell cause the field to dissolve after a certain number of individuals have stepped through it.

History
Note that Energy Field was originally an umbrella term for all the types of magical fields: Poison Field, Fire Field, Sleep Field and Lightning Field, and the same spell would be used to create any of them. Later (after Ultima IV), different spells were designed for each of the fields, and the previous Lightning Field came to be known simply as Energy Field. However, at times the four spells are still called "energy field spells".

Trivia

 * In Ultima VI, this spell, known as Poison Mist, has Words of Power and reagents very similar to the spell Poison Wind from previous games. However, its effect is actually to create a poison field.