Major image question

[Jon_Dahl]

I can imagine that this been asked before, but my Google Fu failed me.

Major Image says the following: "The image disappears when struck by an opponent unless you cause the illusion to react appropriately."

So we have an illusionary wolf. A fighter hits it successfully with his sword. Which of the following options are available?

A. The wolf can appear automatically wounded by the hit, but the fighter gets a new Will save to disbelieve the glamer. They can continue like this indefinitely. However, if the caster does not make the wolf appear wounded each time it is hit, it will disappear. Making the wolf "react" to the hits requires no effort from the caster and the caster can make wolf react to anything at any time, but he or she has to be able to observe the figment in order to make it react to the events.
B. The wolf can appear wounded or even die, but only when it is its caster's turn. This will appear totally fake and even pathetic (see the video below), because the sword will pass through the wolf (all onlookers will automatically disbelieve the illusion) AND the reaction will happen at the caster's turn, plus the caster will spend a free action or a move action to direct the illusion. The delay between the action and the subsequent reaction will look ridiculous: https://www.youtube.com/watch?v=1LwL-xw7Zyk
Unless the caster uses his or her time to make the wolf react to events, no matter how ridiculous it looks like, the wolf will disappear. Nevertheless, the wolf is a joke and its only saving grace is that it will continue to confound everyone who sees the wolf for the first time at some later point.
C. Something else?

[Jon_Dahl]

I will also add what I do as the DM: "Well, you hit the wolf so now you know it's an illusion. You can forget about it now." And then we will ignore the whole thing. If someone asks, it's gone.

[Fizban]

A. The wolf can appear automatically wounded by the hit, but the fighter gets a new Will save to disbelieve the glamer. They can continue like this indefinitely. However, if the caster does not make the wolf appear wounded each time it is hit, it will disappear. Making the wolf "react" to the hits requires no effort from the caster and the caster can make wolf react to anything at any time, but he or she has to be able to observe the figment in order to make it react to the events.
As a concentration spell, it already requires effort from the caster at all times. But yes, you need to see what's going on to guide the spell, and if you stop concentrating then you can't make it react to anything anymore.

If an attack succeeds against a figment, the weapon will pass through the illusion, automatically revealing it. Presumably the reaction you need to provide for a confirmed hit is making the image take a wound, one that visibly matches the fact that the weapon met essentially zero resistance when it "struck." Whether this is possible is up to the DM, and depends heavily on the DM's understanding of the hit point system: every hit draws blood, but only the hit which drops you below 0 is ever a severe bleeding wound (aside from special abilities).

Alternatively, you could use knowledge of the armor class system and one-sided information: the person attacking does not know the AC they're targeting, only what they're told they see, and lots of "misses" in the AC system are actually hits to armor, shield, or natural armor. A wolf's natural armor comes from its fur, while a bladed or piercing weapon could cut or pass through the fur without harming the wolf: an attack that "missed" due to "natural armor," even if the illusion's 10+size AC was hit.

You get a save against illusions when you "interact" with them, even a failed attack is still an action performed against the "creature." Alternatively, one could focus on the fact that attacks which miss often do so because of physical contact, but the illusion's (low) AC of only 10+size means that any miss is by definition one that would not have had such contact, so a missed attack might not give a free save.

Incidentally, all of this is why the savvy illusionist would try to imitate some sort of incorporeal undead, if they really needed a creature illusion to fake a combat.

B. The wolf can appear wounded or even die, but only when it is its caster's turn. This will appear totally fake and even pathetic (see the video below), because the sword will pass through the wolf (all onlookers will automatically disbelieve the illusion) AND the reaction will happen at the caster's turn, plus the caster will spend a free action or a move action to direct the illusion. The delay between the action and the subsequent reaction will look ridiculous:
Unless the caster uses his or her time to make the wolf react to events, no matter how ridiculous it looks like, the wolf will disappear. Nevertheless, the wolf is a joke and its only saving grace is that it will continue to confound everyone who sees the wolf for the first time at some later point.
I mean, illusions aren't nearly as strong as some people claim they are, but if you rule that they're just useless then yeah they're useless.

[Seto]

Yeah, I think that clause exists in relation to the "Concentration + 3 rounds" duration. You're able to make it react (in real-time) if you're still concentrating on it. Basically, if you want your illusion to be a momentary distraction in combat, then you just cast it, never bother to concentrate, and it will last three rounds. But you're already busy doing other things and casting other spells, so you can't keep up the charade if somebody interacts with it.

If on the other hand you're actually willing to put in effort and concentrate on your illusion, then you can make it more believable for a longer time.

This is also why, as a good rule of thumb, illusory creatures are good when you can concentrate on the illusion, and want a prolonged interaction with your enemies. If you're just casting it without concentrating, creatures are a poor choice. You're better off making it look like something that's supposed not to react visibly to attacks, and that your enemies will be wary interacting with, like a Wall of Fire or a Prismatic Wall (bonus, it also blocks line of sight of the creatures who believe the illusion... meaning, them but not you).

[Gruftzwerg]

I can imagine that this been asked before, but my Google Fu failed me.

Major Image says the following: "The image disappears when struck by an opponent unless you cause the illusion to react appropriately."

So we have an illusionary wolf. A fighter hits it successfully with his sword. Which of the following options are available?

...

C. Something else?

The sentence you quoted is referring to whether or not you are concentrating on it atm. For "a reaction outside of your turn" you need to either have cast the spell (counts as concentrating on it) or used a standard action to concentrate on it in your last turn.
This is due to the duration "Concentration +3 Rounds", where you can stop concentrating for up to 2 round to do something else, e.g. cast other spells or switch Concentration between different spells (or even several Major Images).

Another good indicator for this is the description of the warlock invocation "Flee the Scene" (FtS).
FtS is a combination of Dimension Door and a special version of Major Image (MI). Let us have a look what it says:

You can use Dimension Door as a spell-like ability; albeit the range is reduced to Short Range. When you use this ability, you leave a Major Image behind in your place that lasts for 1 round. The image reacts to attacks as if you were concentrating on it.
FtS has a special MI that reacts to attacks as if you were concentrating on it.
This confirms that the general rule for Major Image requires that you are concentrating on it to react properly.
Which leads to my original argument that you have to either have cast it or concentrated on it on your last turn to have it react properly.


edit:

The Attack Roll to hit the Illusion:
While this is not explained in detail, we can extrapolate the rules needed. An Illusion can only have the Touch AC of the resembling thing, since it has no substance. See Mirror Image where the illusionary images only have touch AC.
Imho this is as close as we can get by RAW.

edit2:

I will also add what I do as the DM: "Well, you hit the wolf so now you know it's an illusion. You can forget about it now." And then we will ignore the whole thing. If someone asks, it's gone.
The Illusion becomes transparent for him. He can still see the illusion (if it should provide any useful information for him) but can also see what is behind the illusion without any problems/penalties.
Further he can communicate the info with his allies and give them a Save roll with a +4 bonus on it iirc (someone correct me if I'm wrong. away from book atm..^^).

[Zarrgon]

Well, C.

It's like A, but the spellcaster must concentrate on the illusion.

There will be a slight delay between when a foe "hits" the illusion of the wolf, and when the spellcaster reacts next round. This "delay" is covered by the saving throw to see thought the illusion.

[Gruftzwerg]

Well, C.

It's like A, but the spellcaster must concentrate on the illusion.

There will be a slight delay between when a foe "hits" the illusion of the wolf, and when the spellcaster reacts next round. This "delay" is covered by the saving throw to see thought the illusion.

By the rules there is no discoverable delay and you are denied the save roll if the caster is concentrating on the image and lets it react accordingly. That is the hole point of concentrating on it.. to prevent the save roll by either denying the interactions by letting it doge if possibe (touch AC) of the image or reacts in a realist way when hit.

You would need to do specific things to deny any realistic illusionary reaction, like:
Try to jump onto the head of an illusionary character. If it hits the touch AC, there is no realistic way to act realisticly, cause the attacker would fall through the illusionary foe after hitting (the touch AC).
But normally you don't stuff like that. And for most attacks it is easy to find a realistic interaction outcome as long as you concentrate on it and thus you prevent the save roll for interaction.