Reverse Illusions

Illusion magic in D&D 5th Edition tends to function a certain way. These spells create some sensory effect which a creature can make an investigation check to discern. Here’s a list of spells that work this way (spell level in parentheses):

  • Minor Illusion (C)
  • Disguise Self (1st)
  • Distort Value (1st)
  • Silent Image (1st)
  • Phantasmal Force (2nd)
  • Major Image (3rd)
  • Hallucinatory Terrain (4th)
  • Seeming (5th)
  • Programmed Illusion (6th)
  • Project Image (7th)
  • Illusory Dragon (8th)

Why are these spells built this way? Because they don’t require a saving throw! When you ask players to roll a saving throw, they know something is afoot.

If we move the saving throw on the normal illusion spells to the front end of the spell, then characters who fail the save can perceive the illusion and characters who pass the save will not. It’s a dead giveaway.

But, what if it wasn’t? What if we subverted that expectation by running a reverse illusion?

Reverse Illusions

You can basically do this for any of the spells listed above by adjusting their mechanics. Call for a saving throw when the spell is cast. Creatures who fail the save can’t perceive the illusion; creatures who pass the save can perceive the illusion. From there, just run it like the normal spell! As usual, you can identify the illusion with an investigation check.


Creatures who fail the save can’t perceive what their allies can, building a sense of horror. Creatures who pass the save can perceive the illusion, but since their allies can’t, they may think they’ve saved against some sort of concealment and now they have the sole privilege of dealing with the threat presented by the illusion.

By subverting the player expectations, we can change the way the party might approach an illusion. Once they’ve figured it out, consider flipping it back and running a traditional illusion, or reverse the reverse illusion. The key to making illusion magic come alive is to keep the players guessing what’s real.

Narrative Logic

But wait, you can’t do that!

Sure we can! It’s just an illusion effect concealed with an illusion effect. When a creature passes the save, they’re overcoming the concealment. Illusions can already be created without a saving throw. We’re not doing anything new. If anything, we’re making the spell weaker!

I hope you can use this spell hack to keep your party guessing with illusions. If you enjoyed this content and want to see more, support us on the ThinkDM Patreon!

2 thoughts on “Reverse Illusions

  1. Rather than using saving throws, consider keeping track of players’ passive investigation scores to determine who does that something is afoot.


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