Creating an Energy Field
Sometimes the caster needs to stop an enemy from advancing any further, and if no attack spells are available, this spell comes in handy. It will create a solid energy field that none can pass, not even the caster. Beside waiting for it to dissolve, which can take a long time, the only other way to get past it is the Dispel Field spell, which will destroy the field.
Lore[]
There are four types of Energy Fields known to the practitioner of the mystic arts: Sleep, Poison, Fire, and Lightning. Their effects are varied, but the magic used to erect them is the same in each instance. Any person attempting to pass through an Energy Field will run the risk of either falling asleep or being poisoned in the case of the first two types; if the field is of Fire then their flesh shall burn as they pass through and they shall feel much pain and anguish; while the field composed of Lightning is impenetrable. The casting of Energy Fields is not difficult and requires only a small exertion on the part of the spellcaster, but the fields are only effective in enclosed areas such as subterranean passages and inside of rooms. The reagents necessary in the casting of these Energy Fields are Sulphurous Ash for the burst of creation, Spider Silk for the binding of forces to a single spot, and Black Pearl for the launching of the spell to a spot away from he who works the magic. It would be a grave error indeed to cast such a spell without the latter component for you would find yourself in the midst of the field!
- from The Book of Mystic Wisdom (Ultima IV)
In Sanct Grav's protective energy provides a strong defense. Its shimmering blueness cannot be entered or passed through. An excellent recourse when a few moments of safety are required, In Sanct Grav is well used to block dungeon corridors fully. Mandrake root is necessary for In Sanct Grav; choose older, tougher specimens for this concoction. Add spider silk to make it impenetrable and black pearl for placement.
- from Book of Lore (Ultima V)