The phantasmal force spell can be broken if the victim examines the illusion and makes a successful investigation check against the spell's DC.

What general guidelines should I use to decide when the victim of phantasmal force should use its action to examine the illusion?

Suppose the caster makes an orc think it is being attacked by a wolf.

Should the orc always examine the wolf until the spell ends? Or should the orc use its action to attack the wolf, defend itself, or run away?


5 Answers 5


Depends on the situation.

There are two things to consider.

The target rationalizes any illogical outcomes from interacting with the phantasm. For example. a target attempting to walk across a phantasmal bridge that spans a chasm falls once it steps onto the bridge.


The target can use its action to examine the phantasm with an Intelligence (Investigation) check against your spell save DC

Given that the targeted creature failed the first save**, no matter how smart a creature is, if it rationalize any illogical outcome it would not use any action to investigate the illusion. This hold true for any direct interaction between the illusion and the target.

But, if there is a situation where the affected creature has a reason to believe it might be an illusion, it can use its action as the rule states. For example, an ally seeing him fighting with a ghost might help him yelling "it is an illusion" or "it is in your head". In this case, the creature has a reason to suspect is an illusion an use its action accordingly.

** The description of phantasmal force says:

The target must make an Intelligence saving throw. On a failed save, you create a phantasmal object, creature or other visible phenomenon of your choice that is no larger than a 10-foot cube and that is perceivable only to the target for the duration. This spell has no effect on undead or constructs

  • 1
    \$\begingroup\$ +1 for an ally's (of the enemy's) assistance in realizing the problem \$\endgroup\$
    – Doug
    Jul 27, 2016 at 16:39

Depends on the intelligence of the orc.

For example, if the orc can see the caster manipulating the illusion, it may be intelligent enough to put two and two together. However, it's just a big, dumb grunt then I imagine it'll likely assume the wolf is real and try to defend against it or attack it.

It would also depend on whether the caster causes the illusion to do something unusual that the wolf would never do, like bound playfully towards the orc and start licking his face.

Either way, if the orc is intelligent enough or the circumstances are correct, then roll for the investigation check. If he has no reason to suspect this is an illusion, then have him do what any normal orc would do during a normal wolf attack.

  • 3
    \$\begingroup\$ It's worth noting the phrase "the target rationalizes any inconsistencies in the illusion." An intelligent target would only be better able to rationalize the illusion. If a wolf acted inconsistent with normal wolf behavior, the target would find some rational reason it might happen. He might, for example, conclude the wolf was trained by another orc. Any indication that it's an illusion would have to come external to the illusion itself. \$\endgroup\$
    – Ethan
    Jul 27, 2016 at 21:19

It depends on the victim and the circumstances.

Consider the following:

  1. How intelligent is the target of the spell?
  2. How out-of-place is the circumstance? (cyclone indoors? earthquake on a ship?)
  3. How long has the illusion been in effect? (My axe went straight through it?!)

For your Orc situation, they are reasoning creatures if not particularly well-educated.

Initially, the Orc will probably be surprised and take some psychic damage from the wolf.

On its first turn under the spell effects, the Orc will probably attack the illusion. This is probably not the first time the Orc has fought a wild animal, and it should know that hitting a wolf isn't the most difficult thing in the world. It may also recognize that, without a pack (strange!) to back it up, the wolf should be no problem at all. This attack will fail to kill the wolf, because it isn't there (or, if he rolls really horribly, this might take a round or two to reach the conclusion that the wolf isn't normal).

The next turn, the Orc might spend trying to disbelieve the illusion. That is, to say, after the target realizes that there's something off about the spell's effect, it may try to investigate its way through the illusion.

Regardless of success or failure, on the next turn the Orc will probably prioritize a different threat: The caster (druid/ranger most likely, then arcane casters) who is most likely causing this unpleasant circumstance, or something doing more than 1d6 damage to it. These priorities will, however, take into account how much damage the Orc will take trying to reach that target.

--Considering the size of the illusion that you can make with Phantasmal Force (10x10), depending on how the caster narrates the illusion, you may also have the Orc react in a way other than receiving damage - i.e. fall prone as it tries to defend itself, or fall over an edge as it panics, or run in terror, fall unconscious from strangulation...

Illusion really leaves a lot of room for flavor, flair and interpretation.


If the target is alone, the target has no cause to investigate because it's own reason and mind is twisted into believing the effect is real, no matter the interaction.

If the target has companions, one of them can try to convince the weirdly-behaving target that he's swatting at nothing, at which point the target can use his actions to make an investigation check. For NPC's, this should involve taking an action, not dissimilar to shaking someone awake. This is a good mechanism for DM's so that the combat doesn't devolve into an argument about metagaming.

Think of it this way: It should take some effort for even a friend to convince you that you're not actually sitting at your desk typing at your computer reading this comment while it constantly drains 1d6 of your psyche. It probably shouldn't involve taxing turns out of players, but it should involve more than a few brief words to be convincing. How about a dog that keeps biting you? How far do you go before someone takes the time to tell you that there's nothing there, as it gnaws at your ankle causing pain?

Failing your save against Phantasmal Force without allies is, and should be, terrifying As a spell, it barely does any damage, and doesn't explicitly allow for applying conditions such as flanking, restrained, or blindness (as I personally disagree with the 'sage' tweet on the subject). What I can say about it is it's designed to impose an action tax on a target while dealing damage, which is both similar to, and different from, Charm Person. The abysmally low damage for a 3rd level spell means it shouldn't be easily circumvented.

As a spell, Phantasmal Force is badly worded, badly ruled (as most illusion spells), and nothing is provided but scattered advice for DM's trying to adjudicate it. I can only treat it as a spell that does what it does: Slowly deal damage to lone targets and burn actions of low INT characters trying to 'investigate' it.

  • 1
    \$\begingroup\$ Usually PC to PC interaction does not use checks. Why do you think telling the ally to make persuasion is a good idea, as opposed to let the victim automatically "realize" it's an illusion and start to investigate? \$\endgroup\$
    – Vylix
    Feb 17, 2019 at 16:15
  • \$\begingroup\$ @Vylix I edited that for Zourin. Zourin, if you like the edit, good. If not, revert it to your original answer and then please address the point Vylix made via an edit. \$\endgroup\$ Feb 18, 2019 at 2:58
  • \$\begingroup\$ I've clarified the post a bit, and I agree, there's no merit to taxing players, but the point was more about creating a mechanism where a DM can handle phantasms without straight-up metagaming them. Spending an NPC action is cheap in terms of cost for a DM, but at least demonstrates a measure of due process for handling the situation. \$\endgroup\$
    – Zourin
    Feb 18, 2019 at 16:46

There's an obvious answer here that nobody in four years has given:

Never - or pretty close to it.

The spell description says that the target can spend an action to investigate the illusion, but that doesn't imply that you as DM should regularly (or even rarely) have them do so. And there are several good reasons not to.


  • The game-logic argument: The spell description says that the target rationalizes away the clear evidence of their own senses, so it's reasonable for them to react similarly to other evidence. Even if, say, an ally warns them about the illusion, it would be reasonable for the target to dismiss that as a joke or a mistake.

  • The consistency argument: As DM, how often do you have your NPCs waste their action by investigating a spell effect that's not an illusion? You should probably have them investigate illusions about that often.

  • The balance argument: Phantasmal Force does low damage and possibly an action tax, at the cost of concentration and doing nothing at all on a save. Comparable spells at 2nd level do 2d6 per round (Flaming Sphere) or 6d6 once (Scorching Ray). PF isn't a spell that the DM needs to invent reasons to negate.

Balance note: some DMs mistakenly think this spell is strong because it "shuts down" the target. The spell description says an affected target believes the illusion is real, but whether they spend any actions dealing with it is entirely up to the DM. If you feel an NPC would ignore the illusion and attack the player who summoned it, nothing in RAW or RAI discourages that.

  • The RP/fun argument: Any player who casts Phantasmal Force in combat probably knows that they're not - in raw mechanical terms - making the strongest use of their spell slots. They made a conscious choice to use a weaker but more thematic spell - probably because thinking up an illusion lets them take an active role in the storytelling. As DM you should consider whether you want to reward or punish such behavior - if you have the NPCs immediately investigate, that's a lot like telling the player to shut up and cast magic missile.

Obviously, none of this should be read to suggest that NPCs aren't allowed to investigate the illusion. If you have a situation where it's logical, necessary, or fun for the NPC to investigate, then obviously they should do so.

But in my experience such cases are incredibly unlikely - there's always something more logical and more fun the NPC could be doing. So as a baseline I'd lean strongly towards never having NPCs investigate Phantasmal Force.


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