D&D 5E Effective Illusions

[Andrew Blair]

Another one. Could you create illusions your party can choose not to disbelieve? Would an illusion of a sack on a medusa's face save the party from the gaze attack? What if your illusion is of a uv light source? Only night vision characters can see as you wander through the underdark. Can an illusion create light? If so, how intensely? Can you strobe a bright light to cause dizziness and loss of night sight for archers?

 

[Andrew Blair]

If an illusion can bend or reflect light, could you make illusory telescopics or microscopic optics?

 

[Andrew Blair]

Holy Christ. If you can do optics with illusions, there is a whole lot of fun you can have with an illusionist. Every army marching would require illusionist training for officers, scouts and engineers.

 

[jaelis]

Simplest way to judge illusion questions like that is to rule they are figments in the mind of the beholder. So they can't reveal any information the caster doesn't already have.

Not the only way to play it, but it works.

 

[Whizbang Dustyboots]

Would a ref allow an illusion of a mirror or an illusion of a reflective surface? Would that surface behave like a conventional mirror? Or would you have to concentrate on what the mirror is reflecting? Night time combat. You make an illusion of a sheet of glass, you throw a stone with light cast on it behind some attackers. Does the illusion reflect light like real glass?

A standard illusion would not work like a mirror. That's why, historically, there's one that explicitly works that way. Unless you're using Gaze Reflection, the illusionist has to keep up with all the reflections through manual changes to the effect.

 

[Andrew Blair]

That makes a fair amount of sense. Many thanks for the clarification. What about light selectivity in an illusion? Can an illusion be used as a customized light source? I was thinking about light sources that can only be seen by people with infravision or ultravision. Or adjustable light sources for non combat environments. What would your take be?

 

[jaelis]

My take: anything illuminated by an illusory source would itself have to be illusory.

 

[Andrew Blair]

So a bait illusion of a fighter with a torch would not illuminate the tunnel ahead?

 

[jaelis]

So a bait illusion of a fighter with a torch would not illuminate the tunnel ahead?

Well, if the area of the illusion was big enough, you could create the illusion of an illuminated area of the tunnel. But otherwise no.

Bearing in my that is just my interpretation of how it works.

 

[jgsugden]

RAW are null on the point, but from my view, illusions must generate light t be seen as there is no surface there for light to bounce off. The light reaching our eyes must come fom somewhere. Of course it must be magical light as it creates different optical results for different people (based on if they have successfully investigated it or not).