A Theory on The School Of Illusion

Below, I present my theory of how the school of Illusion works. I do not offer any justification, simply state the facts. In particular, I don't indicate where this theory differs from the official TSR policy. If you want justification, read the TSR discussion

Since TSR has divided the school of illusions into illusions and phantasms, it makes it difficult to distinguish between the two different meanings of illusion (school or magic type). To avoid confusion, I will always make it explicit, by referring to the school of illusion, or illusion magic, depending on whether I am refering to all types of magic within the school of illusion, or the specific type of magic affecting sensory perception.


Illusion School: The Sub-Schools

The school of Illusion consists of three sub-schools:

  1. Illusion: Magic that affects the sensory perceptions of targets. Although it is sometimes useful to describe such effects as if light, smell and temperature are being controlled within an area of effect, this is not what is actually happening. Instead, illusions are entirely mind-affecting (there is no physical component to this category of illusion).

  2. Phantasm: This type of magic affects the emotions and feelings of an individual, rather than sensory perceptions. As well, phantasms can act to change an individuals mental state with respect to what is likely, acceptable and normal. For this reason, most illusion magic is supported by at least a small amount of phantasm magic; the phantasm magic makes the recipient more likely to accept illusionary sensory perceptions.

  3. Shadow : The only way that spells in the school of illusion can cause real physical damage is if they access the Plane of Shadow. This type of magic creates an actual physical force that exists independent of the belief of targeted individuals. Shadow magic makes illusions all the more believable because a small amount of the physical sensation being experienced is real, not illlusionary.

Illusion School: Spell Categories

The various spells in the school of Illusion can be divided into five different categories, as follows:

  1. Concentration

    Spells in this group use illusion magic to modify sensory perceptions, and phantasm magic to make these perceptions more believable. The content of the illusion is dictated by the caster, either via real-time mental control, or via a visualized sequence of events. Although concentration is not strictly necessary for all of these spells, the most flexibility and realism is obtained when the caster is actively concentrating on the content of the illusion.

    Due to the flexibility allowed by these spells, they can be extremely powerful, depending on the creativity, intelligence and (general/specific) experience of the caster, as well as the recipients.

    All of these spells affect all creatures within a certain area of effect. This means that the spell is not targeted at specific individuals, so the caster does not need to know of the existence of an individual for the illusion to affect that individual. However, the caster must maintain a 3-D image of the desired illusion at all times. Normally, such a task would be impossible for even the most profoundly intelligent of individuals, because people are very much used to seeing others from one perspective, not all possible perspectives. However, the spells in this category provide more than just the ability to affect the sensory perceptions of individuals; they also substantially increase the spatial-temporal capabilities of the caster, allowing calculations of 3-D images that would normally be impossible.

    Determining whether targeted individuals detect and disbelieve these types of spells can be a difficult process. Rules for handling this are discussed later. However, note that since these spells only affect individuals within the area of effect

    This category of illusion spell is usually the reason why individuals decide to specialize as illusionists. Illusionists are by nature creative and imaginative, and have excellent spatial-temporal abilities to begin with. The augmentations provided by these spells tend to be extremely appealing to such individuals, and the challenges in maintaining a complicated illusion becomes its own reward.

  2. Sensory

    This group represents spells that are specialized versions of the concentration category above. As such, spells in this group use illusion magic to modify sensory perceptions, and phantasm magic to make these perceptions more believable. The amount of control the caster has over the illusion content is severely limited, but the power of the resulting illusion is much greater than a similar concentration-based spell.

  3. Phantasmal

    Spells in this group use phantasm magic to modify the feelings, emotions and/or beliefs of targeted individuals. Illusion magic may be used to augment these feelings, emotions or beliefs via sensory perception modification, but the primary effect of the spells in this category are due to phantasm magic.

  4. Concealment

    Spells in this group use illusion magic to conceal objects or entities from sensory detection and other forms of detection. Depending on the specific spell, phantasm magic may be (strongly) used to emphasize belief in one sense over another (for example, vision over touch).

  5. Shadow

    Spells in this group draw energy from the Plane of Shadow, creating an actual physical force that causes real damage, and that exists independent of the belief of target individuals. Almost all of the spells in this category use illusion and phantasm to make the spell even more potent, but even individuals not affected by the illusion and phantasm components will still be affected by the shadow magic.

Here is a table listing all of the illusion spells from PHB2, and their categories in my theory.

Concentration Sensory Phantasm Concealment Creation
Phantasmal Force Change Self Nystul's Magical Aura Invisibility Minor Creation
Improved Phantasmal Force Blur Spook Invisibility, 10' Radius Shadow Monsters
Spectral Force Audible Glamer Leomund's Trap Improved Invisibility Demi-Shadow Monsters
Advanced Illusion Ventriloquism Misdirection Vacancy Major Creation
Permanent Illusion Fool's Gold Whispering Wind Shadow Door Shadow Magic
Programmed Illusion Mirror Image Illusionary Script Mirage Arcana Demi-Shadow Magic
Wraithform Fear Veil Shades
Illusionary Wall Phantasmal Killer Mass Invisibility Shadow Walk
Seeming Hypnotic Pattern Sequester Simulcrum
Project Image Rainbow Pattern Screen
Dream Hallucinary Terrain
Eyebite
Mislead
Weird


General Notes

This section describes some comments about how the school of Illusion affects the real world. They are mostly directed at the category of concentration-based spells (since these are the most difficult to adjudicate properly), but are usually also applicable, if to a lesser extent, to the other categories as well.

Detection and Disbelief

Both illusion magic and phantasm magic work solely on the minds of targeted individuals. As such, they only work if the targets believe that the induced sensory perception, emotion, feeling or belief is real. In terms of game mechanics, disbelief is determined by a saving throw versus spells, with various modifiers applied based on the caster, target, and situation. Detection is determined either by DM decision, or by an ability check (usually against intelligence, to represent observation skills).

Normally, individuals believe their own senses, emotions, feelings and beliefs, because these are internal properties that are considered inviolate. Thus, chances to disbelieve an illusion or phantasm are not automatic; the targeted individual must detect some anomaly that justifies disbelief. This can be inconsistencies between different senses, unexplained feelings, and concious monitoring of ones internal state. In terms of game mechanics, detection is usually determined by intelligence checks.

If detection occurs, the exact effects depend on the category of spell, and, in some cases, the specific spell, in question. In most cases, detection allows a chance for disbelief (i.e. a saving throw), and if the save fails, the character ignores the anomaly or whatever inconsistency was detected. However, if the save succeeds, the individual knows the illusion/phantasm for what it is. In such cases, the individual can still experience the effects of the illusion/phantasm, but can also decide not to experience them. The illusion/phantasm loses all potential to cause distraction or any other effect on the individual, even when the individual is experiencing the illusion, unless they intentionally fully submerge themselves in the illusion again with a concious act of will.

For concealment spells, the chance that individuals will remember detected anomalies if they fail their chance to disbelieve is dependent on how much phantasm exists in the magic. Low level concealment spells have very little phantasm, so, for example, detecting an invisible individual but failing to disbelieve does not mean that the target forgets about the anomaly - they will know that someone is around, but invisible. On the other hand, if they also manage to disbelieve the illusion of invisiblity, they will actually be able to see the supposedly invisible individual.

All of the above discussion applies only to illusion and phantasm magic. Shadow magic is real, and disbelief has no effect on its reality. However, most spells use shadow magic in conjunction with illusion and or phantasm magic; disbelief of the illusion/phantasm component will imply that no damage from that component is sustained.

Damage

Individuals who believe they experience damage, due to sensory input caused by illusion or phantasm magic, do not actually receive any real damage. However, if they are reduced to 0 hitpoints, they collapse in a faint, and will revive in 1d3 turns, at which time they are eligible for save versus spells at +4 to see if they are still under the influence of the illusion (assuming it is still in effect). Only in extreme cases will such individuals actually be required to make a system shock roll in order to determine if they die or not.

Combat

Obviously, a well rendered illusion of a monster is believable, but if only illusion magic is used, there is no way to generate the illusion of a 10th level fighter, rather than just an illusion of a person wearing armor and carrying weapons. However, phantasm magic modifies emotions, feelings and beliefs, so, in conjunction with the sensory illusion of a person wearing armor and carrying weapons, phantasm magic can make targets believe that the illusion has a high (or low) degree of skill.

It is possible to make an illusion of a particular monster, or a character of a specific class and level, whenever a phantasm component exists in the spell. The phantasm magic is used to convince the target(s) that the image seen is skilled. In general, how skilled the target believes the illusion to be depends on both the targets past experiences with real versions of the illusion, and the skill-level of the caster.

Exact appearances

It is usually more difficult to create an illusion of reality than an illusion created entirely from the mind of the caster. For example, creating an illusion of a specific person is more difficult than creating an illusion of a generic person.


Last updated: Thu Dec 12 1996 at 15:30 (AETF - aetf@cs.ualberta.ca)