Major Illusion - Moving it after it has been interacted with

[nickl_2000]

So, the illusion spells says that it turns faint and can be seen through when someone figures out that it is an illusion.

What happens if you move the illusion and change the image? Does it make it "real" again to people who discovered the last past was an illusion? Or is it once disbelieved, forever disbelieved for that casting?

[RSP]

So, the illusion spells says that it turns faint and can be seen through when someone figures out that it is an illusion.

What happens if you move the illusion and change the image? Does it make it "real" again to people who discovered the last past was an illusion? Or is it once disbelieved, forever disbelieved for that casting?

I play it as anyone who knows it’s an illusion can see through it until that illusion expires. So it’s character-based: it can be faint and see through to one character but appear real to another.

I’m not sure what you mean by change the image. My understanding of the spell is you choose what the illusion is of, for example an Ogre. That Ogre can move around and in doing so, will look like a real Ogre moving around; in that way the illusion can “change” how it appears.

However, once cast, that illusion of an Ogre cannot be made into a Wyvern.

[Mastikator]

I play it as anyone who knows it’s an illusion can see through it until that illusion expires. So it’s character-based: it can be faint and see through to one character but appear real to another.

I’m not sure what you mean by change the image. My understanding of the spell is you choose what the illusion is of, for example an Ogre. That Ogre can move around and in doing so, will look like a real Ogre moving around; in that way the illusion can “change” how it appears.

However, once cast, that illusion of an Ogre cannot be made into a Wyvern.

I agree with this. Also Malleable Illusions from Wizard: School of Illusion lets you change the nature of the illusion so I'd let that (and only that) change an ogre into a wyvern.

[Kyovastra]

A literal reading of the RAW would probably be that it's the same illusion and remains identifiable as one, but I don't think 5e's rules are usually meant to be read like that, as it doesn't make sense you could then instead pull a 6th-level major image out of a leomund's secret chest and it'd work better than if you were to use the previously identified major image to do the exact same thing with a new illusion - purely for the arbitrary reason of it being a different major image, which can't be known to the observer inspecting it (sure, it's magic, but identifying illusions seems more like it's meant to be a general rule they included in specific spells for game reasons, rather than a part of a wizards' design of the spells themselves).

RAI seems to me that it wouldn't be immediately identifiable if you changed the "object" into a different illusion, but if someone previously identified a major image as being an illusion, they'd be more likely to want to disbelieve something else right after and want to investigate it to make sure it's real. That seems the simple and reasonable way. Plus, it prevents needing a leomund's recycling bin of illusions you go through reusing each one with different NPCs to help reduce your illusory Weave-waste of feint images.