In SR5, the way area illusion spells (such as Trid Phantasm) work is by interacting with the environment within the affected area such that anyone, whether perceiving the area normally or technologically, will see the illusion instead of the actual area.

Are 5e mages able to remove the effects of such an area illusion from certain individuals?

For example, the runners come across a hallway monitored by a series of closed-circuit cameras the decker is unable to hack. If the mage were to cast trid phantasm (with the chosen scene being the empty hallway), would the runners within the spells sphere of influence see only themselves (the spell completely affects them as well as well the cameras) or would the mage be able to designate them as being able to see through the illusion? Or does the illusion function as a sphere affecting only those outside the radius looking in?


1 Answer 1


RAW says you can resist a physical illusion spell with the right roll, but it does not clearly specify what the end result of resisting a physical illusion spell is (though it implies the result is the same as resisting a mana illusion). Spells like Trid Phantasm actually change the properties of the light particles in a space. They project real light, from a manipulated source. The light isn't the illusion, the source of the light is. So you can't see through them by resisting them. Light is light. You see the light that's there, regardless of whether the source of the light is there.

Think of it like a Con (deception) roll. If you fail to successfully lie to someone they don't necessarily know the truth. They just know that you're lying. They still have to try to deduce what the truth is based on the circumstances of the attempted deception. They didn't hear the truth in your lie. They surmised it (possibly incorrectly).

So if you project an empty room using Trid Phantasm, and an NPC successfully resists the illusion, they know it's an illusion, but they still see the empty room (light is light). They have to deduce the truth based on what they know of the circumstances. Subsequently, I would say the caster's allies can't see through it either. Since Trid Phantasm actually alters the light in the space (which is why it works on cameras), even knowing it's fake won't change what you see.

The rules as written really don't specify though, and they kind of imply that physical illusions are resisted the same way as mana illusions (with presumably the same results). That doesn't make sense, but I suspect it's what is intended. Physical illusion spells create all kinds of problems like this when you really think about them. How do you change the properties of light in a space without changing the physical properties of the space? It gets into serious quantum craziness at that point, and illusionists capable of casting Trid Phantasm quickly become gods (if you can manipulate the physical forces required to alter light like that, you can do more with those forces than make a room look empty).

You could decide to handwave away the sticky issues of physics, and just play the game with a suspension of disbelief (answering the question however your group feels most comfortable). Or you could really try to figure out the specific details of how physical illusions work, and why illusionists can't also teleport themselves or rip their enemies apart with the same gravitational forces they bend light with.

I'd rule the players can't see through it, mostly for flavor. The only question I'd ask then is whether they can see themselves. Since they're removed from the illusion for all other observers, why wouldn't they be removed for themselves as well? This could also be used to tip off the guards. If a guard steps out for a smoke break and notices themselves disappear in that particular hallway ("Hey, where did my hands go?"), they'll probably figure out something is wrong.


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