How would you rule this?

[quiet1mi]

A level 12 Beguiler cast Major Image on an enemy soldier in combat...

The major image is that of flames. Major image is an illusion also includes temperature...

If I create the "Illusion" of super heated flames upon the skin of my opponent, would they be incapacitated from the pain... (Naturally they would get a save from interaction with the illusion)

[Riffington]

It doesn't cause pain, only temperature. Above a certain temperature, this may cause a certain amount of disbelief.

[Comet]

It doesn't cause pain, only temperature. Above a certain temperature, this may cause a certain amount of disbelief.

Yup. It feels very hot, but for some reason no actual burning happens. At that point the mind goes 'bwuh?' and disbelief happens.

[Susano-wo]

HE would have a chance to disbelieve, sure. But it says it affects temperature. No this does not mean actual temperature, but the individual would feel like it was actually that hot

He may or may not look at his arms and wonder why his skin isn't charring, etc, but he might be too panic-ed. That's what the disbelieve is for (with circumstance bonuses if its fairly unbelievable). Paralyzed with pain? maybe. You can feel phantom pain from limbs that don't exist, so who says that the illusion wouldn't cause your brain to create false pain?

[Ilmryn]

A level 12 Beguiler cast Major Image on an enemy soldier in combat...

The major image is that of flames. Major image is an illusion also includes temperature...

If I create the "Illusion" of super heated flames upon the skin of my opponent, would they be incapacitated from the pain... (Naturally they would get a save from interaction with the illusion)

He would probably not get more "incapacitated from pain" than if you cast a fireball. It might get him to jump into a nearby lake if there is one handy...this might be a good combo with the example of the use of a suggestion spell in the PHB. (That pool of acid is actually nice water, wouldn't a dip be refresing?)

[PersonMan]

Better to just make it look like his spear/shield is on fire. If he fails his save he'll probably throw it off/away before he goes "wait, the fire isn't burning me".

[Snake-Aes]

A level 12 Beguiler cast Major Image on an enemy soldier in combat...

The major image is that of flames. Major image is an illusion also includes temperature...

If I create the "Illusion" of super heated flames upon the skin of my opponent, would they be incapacitated from the pain... (Naturally they would get a save from interaction with the illusion)

It wouldn't. By the rules, damage itself doesn't cause pain enough to incapacitate someone. The fire may "hurt like 4d6", but 4d6 fire damage doesn't stun your characters, does it?

All it would do is entitling him a save to realize that it isn't really burning..and if he fails he'll behave accordingly to the fire(usually waste time trying to put off the fire...but if he thinks fighting is more important than the pain, then he'll fight)

[Susano-wo]

Yeah, by rules its pretty much up to the DM what actions something so broad would cause in someone.

BUt the damage issue is a good point. perhaps causing phantom damage is a good solution? decide, say, 4d6 or 6d6 or whatever damage a round until he disbelieves, and when he does the damage disappears. If he falls unconscious, then he remains that way until he disbelieves or the illusion times out

Not really RAW, bu there's not a lot of RAW on something like this, really, and I think its keeping with raw spirit while rewarding creative use of major image

[--Lime--]

...this might be a good combo with the example of the use of a suggestion spell in the PHB. (That pool of acid is actually nice water, wouldn't a dip be refresing?)

^ Love this.

Also, I'd adjust the disbelief DC to account for the temperature. To me it seems like it can't mimic the hurt factor of actual fire, so I don't know about "phantom pain" since it's a phenomenon precisely because it's not common.

You might have him stop, drop and roll if he doesn't disbelieve it, which would be funny. I also like the idea of casting it on the enemy's weapon. It would be reasonable then for the sword to feel hot before it burned his skin, and disbelief would be even harder.

[Ernir]

Being on fire is like 1d6 damage/round. Your opponent isn't falling unconscious from that anyway any time soon, unless he's a complete pushover.

[Keld Denar]

The problem with having illusions cause damage is there is already a sub-type of illusion that IS quasi-real. Thats the Shadow subtype. If you make Shadow Fire, it WILL burn someone. Major Image only creates figments, and figments aren't real, and can't EVER directly cause harm.

It sounds like you are trying to dig a hole with a screwdriver. There are already shovels in the game...dig with them.

[Yuki Akuma]

Fire doesn't hurt because it's hot. It hurts because it burns you. It damages your cells and causes your pain receptors to become damaged and yell at your brain "Pain! Stop it!".

The illusion wouldn't hurt. It would just feel hot, and make the target go "Bwuh?" and roll a will save.

[molten_dragon]

I'd rule it that if he failed his save, he'd spend a round or two trying to put out the flames before realizing they weren't actually burning him and ignoring them after that point.

That would of course be the perfect time to set him on fire for real, since he'd then probably ignore it for a couple rounds.

[valadil]

Will save. If he fails, subdual damage (though he thinks it's real).