If an Illusion wizard casts Phantasmal Force on themselves, can they use the Illusory Reality feature to make things only they can see real?

Question

Here's the intent: an Illusionist Wizard casts Phantasmal Force on themselves. Assuming they fail their own save, they proceed to make illusions of things only they can see. For example, a bridge to cross a chasm.

Then, they use Illusory Reality to make that illusion real. The bridge they see in their head now becomes real -- but it also only exists in their own mind.

Let us assume the wizard can use Illusory Reality on Phantasmal Force. Then if the wizard's party mates were to step on the bridge that they can't see, would they fall?

Answer 1

Sure, this works. The bridge doesn't 'exist only in their own minds', though. It becomes real:

When you cast an illusion spell of 1st level or higher, you can choose one inanimate, nonmagical object that is part of the illusion and make that object real. You can do this on your turn as a bonus action while the spell is ongoing.

When you create the phantasm, only you can see it. When you decide that it's real, suddenly everybody else can see it too. Note that convincing yourself to use Illusory Reality on illusions you have convinced yourself are real may be tricky, depending on your DM. Bridges are a pretty safe bet, though. Bridges totally seem like something I might have tricked myself into thinking was there when really it wasn't there so that I could get to the other side. That and staircases. And it never hurts to give it a shot.

Answer 2

It won't work, because the character believes it's already real

The text of the spell states, (emphasis added)

While a target is affected by the spell, the target treats the phantasm as if it were real. The target rationalizes any illogical outcomes from interacting with the phantasm.

This means that the illusionist believes that the illusion that he/she is seeing is already real, and is thus not a valid target for illusory reality. This doesn't really make sense, but the spell is very explicit that any illogical outcomes are rationalized away. Perhaps they think that casting and concentrating on the spell is necessary to reveal the bridge, or some magic mishap made the bridge real. Still, the bridge is still not real, and the wizard's party members would fall through it (in fact, they wouldn't even know that it's there).

Moreover, if the wizard does somehow realize that the illusion is just an illusion, the spell ends and the illusion disappears:

If the check succeeds, the target realizes that the phantasm is an illusion, and the spell ends.

Your scenario depends on metagaming

Your scenario's logic requires that the wizard hold contradictory beliefs: that the illusion is real, and that it's not. The only way to resolve the contradiction, and thus use this "exploit", is to use out of character knowledge that the character itself cannot have. Accusations of metagaming often get quite hairy, but I think that this is one of a few clear-cut situations.

Answer 3

No, the PCs will not fall

The bridge is now real in that scenario, the other characters may now see it, too, since it has become real, for all intents and purposes.

Really, the only contention is whether or not a Wizard can use Illusory Reality with something he thinks is not an Illusion, but if the DM OKs the use of Illusory Reality with the effects of Phantasmal Force, then the interaction between the two is clear: the illusion becomes real.

Answer 4

Only in very specific and contrived scenarios

I agree with Icyfire's answer that it cannot normally work because the illusionist under the effect of phantasmal force would believe that it is real since phantasmal force say :

While a target is affected by the spell, the target treats the phantasm as if it were real.

And as such, the wizard wouldn't normally be able to use it's Illusory Reality on it because it can only be used on illusions.

But it can work if the wizard is not the one making the choice of using his ability. For that he would need an ally and some coordination, it would go :

1. Ally cast dominate person on the wizard.
2. Wizard inform his ally of what illusion he intend to make with phantasmal force (a bridge for exemple)
3. Wizard cast phantasmal force and is convinced the bridge is real, start to walk toward the bridge
4. Ally order the wizard to make the illusory bridge in front of him real. The wizard will then try to make the illusory bridge in front of him real even if it doesn't make sense to him since dominate person specify

   You can use this telepathic link to issue commands to the creature while you are conscious (no action required), which it does its best to obey.

5. The wizard will then try to make the illusory bridge in front of him real, even though it seem nonsensical to him since he doesn't believe it is an illusion. He use his Illusory Reality class feature which make the bridge real but only for him.
6. Wizard walk on the bridge. He his confused about their plan to use several spells and to mess around with his mind to make an already real bridge real.

As a bonus, the wizard might start to question his own reality and examine the bridge. Doing so allow him to make an intelligence (Investigation) check and succeeding would make him realize the now real bridge is actually a phantasm, ending the spell.

I used the spell dominate person because it specify the target try his best, but it might work with the suggestion spell which make this strange combo a lot less costly in therm of spell slots but more vulnerable to personal interpretation.