Phantasmal Force can create the illusion of a creature or phenomoenon, and will deal 1d6 psychic damage per round because of the victim believes that it is real.

What will happen if you create the illusion of something that deals a type of damage the target is immune to? For example, imagine you are facing an imp shapechanged to rat form and not realizing what it is, you call forth a pool of lava under it.


2 Answers 2


Yes, the creature will take damage

Here's what the text of Phantasmal Force says about dealing damage:

Each round on your turn, the phantasm can deal 1d6 psychic damage to the target if it is in the phantasm’s area or within 5 feet of the phantasm, provided that the illusion is of a creature or hazard that could logically deal damage, such as by attacking. The target perceives the damage as a type appropriate to the illusion.

Note that the requirement is "could logically deal damage" and not the more specific "could logically deal damage to the target". Additionally,

The target rationalizes any illogical outcomes from interacting with the phantasm.

So the imp in the illusory pool of lava will feel like it is taking fire damage, even though it is immune to fire damage. It will find some way to rationalize this illogical outcome, e.g. "this lava is so hot it can even hurt me," or "this lava contains something caustic that is burning me" (in which case the imp might perceive the damage type as acid rather than fire).

Ultimately, the spell's target takes the psychic damage first, and then it has to come up with some rationalization for why it took damage, even if taking damage seems like an illogical outcome based on the nature of the illusion. Also note that contrary to my above examples, the rationalization doesn't have to include a specific reason. The creature's thinking could simply be "this lava shouldn't have hurt me but it did and I don't know why".

  • 3
    \$\begingroup\$ Seems reasonable, but what about "The target perceives the damage as a type appropriate to the illusion." Wouldn't the imp perceive the damage as fire, as fire appropriate to the lava portrayed, and not as acid or particularly hot fire - and then have to rationalize why it was being affected by normal lava-induced fire damage? \$\endgroup\$
    – Kirt
    Nov 20, 2022 at 6:26
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    \$\begingroup\$ @kirt Another way to look at it is that the target takes the damage first and then has to rationalize why it took damage after the fact, even if it would be illogical for it to have taken damage. \$\endgroup\$ Nov 20, 2022 at 12:07
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    \$\begingroup\$ @Kirt That’s the horror of phantasmal force: things that shouldn’t be hurting me are hurting me. \$\endgroup\$ Nov 20, 2022 at 13:25
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    \$\begingroup\$ Rationalising "could deal damage" in such a generic manner doesn't make any sense to me, that's very rules lawyer like to match a certain interpretation and you are using standard interpretations on what can deal damage. To an imp fire isn't something that can deal damage, in the hells it probably deals damage about as often as people die trying to fasten their trousers - It can happen, but you wouldn't say trousers "caused damage" \$\endgroup\$
    – SeriousBri
    Nov 21, 2022 at 22:59
  • \$\begingroup\$ @SeriousBri I mean, yes, at some level everything is relative. Someone else brought up the example of a fire elemental and water, which is not normally regarded as a source of damage. There is probably nothing in existence that can deal damage to all creatures except perhaps something like a sphere of annihilation. Regardless, this is the interpretation that makes the most sense to me. Some amount of subjectivity is going to be required for adjudicating this spell, not unlike many other illusion spells. \$\endgroup\$ Nov 22, 2022 at 0:41

Could not take any damage

A DM might have something to say here because of the last line in the spell's description:

The target perceives the damage as a type appropriate to the illusion.

Since the Imp perceives the lava as being fire damage, it doesn't have any reason to think it should take any damage from it, therefore it won't. Unless you explicitly say you make a pool of caustic lava with burning and acidic properties (which would be another story), the monster might not take any damage.

Fluff aside, it should

If we take the spell's RAW description and effects, skipping on the justification as to why the monster thinks they're taking damage, the spell deals psychic damage, which the monster in particular might not be resistant/immune to.

Getting picky

Another line on the spell says this:

Similarly, a phantasm created to appear as fire, a pool of acid, or lava can burn the target.

If we are picky, we can point out that it says "can" and not "will".

Spells do what they say they do. No more, no less.

Simplifying, if the Imp perceives the damage as fire damage, it will not feel affected by it and won't take any damage. The spell doesn't say it ignores resistances or immunities, so unless the target feels it should take damage by it, it won't.

So for example it doesn't make any sense for a pool of water or localized rainy cloud that will hurt a fire elemental to also hurt a goblin since it is just some water.

  • \$\begingroup\$ I would appreciate an explanation for the downvotes. It could be that I am misinterpreting the spell and could help to edit my answer to avoid misguiding people. \$\endgroup\$ Nov 22, 2022 at 7:54

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