If I used Mirage Arcane to transform a lake of water into a lake of lava…

7 thoughts on “If I used Mirage Arcane to transform a lake of water into a lake of lava…

  1. D. Walker says:

    Mirage Arcane is one of those spells that really shouldn’t work the way it does, given what it is supposed to be.

    It’s supposed to be an illusion, but it works more like a warping of reality. The spell entry itself gives the example of making open fields or a road resemble a crevasse. That means you can dig a hole in the ground which people can actually fall into with this spell.

    That’s not an illusion – that’s transmutation. You’re not just making people perceive solid earth as an open pit, while in reality it remains unchanged – you’re actually physically turning the earth into empty air temporarily.

    If you cast the spell to make a pit or crevasse, and someone falls in it, and you dispel the effect, now they’re buried alive underground. There’s no possible way that can be an illusion.

    • Michael Scott says:

      I very much disagree with this interpretation, and I think it demonstrates a lack of understanding of what the School of Illusion is capable of at higher levels.

      From the PHB on the Wizard School of Illusion Subclass:

      “You focus your studies on magic that dazzles the senses, befuddles the mind, and tricks even the wisest folk. Your magic is subtle, but the illusions crafted by your keen mind make the impossible seem real. Some illusionists — including many gnome wizards — are benign tricksters who use their spells to entertain. Others are more sinister masters of deception, using their illusions to frighten and fool others for their personal gain.”

      And from the ability “Illusory Reality” :
      “By 14th level, you have learned the secret of weaving shadow magic into your illusions to give them a semi-reality. 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. The object remains real for 1 minute. For example, you can create an illusion of a bridge over a chasm and then make it real long enough for your allies to cross.

      The object can’t deal damage or otherwise directly harm anyone.”

      And there are many powerful illusion spells that can make things effectively real.

      Aside from Mirage Arcane, there’s
      Creation, which “pull[s] wisps of shadow material from the Shadowfell to create a nonliving object,”
      Simulacrum, which makes a physical clone of yourself that can do everything you can do, including casting powerful magic,
      Illusory dragon, which makes a tangible dragon “because of the shadow stuff used to create it,” which can deal damage even on successful intelligence saving throws.

      It’s clear that some Illusion spells can and do make real, tangible things in reality.

      Transmutation is about changing existing energy and matter. Mirage Arcane doesn’t do that. A transmutation spell would leave terrain permanently altered. Mirage Arcane creates an illusion so powerful that, for the duration, it is tangible and its effects are real. But when the spell completes or when it is dispelled, nothing about the original terrain will have been altered, unlike with a transmutation spell. Moreover, the spell says nothing about what happens to creatures trapped in an illusory hole in the ground when the spell ends. You made the assumption that the ground would swallow them up and they’d be permanently buried. But the more likely outcome would be that they would appear on the ground somewhere within the vicinity of where the hole was that they fell.

      TL;DR Your rant does not accurately describe the School of Illusion as is written in the rules. Powerful Illusions CAN create real–or at least tangible–things, temporarily. Transmutation spells permanently alter existing energy and matter, which Mirage Arcane does not.

      • Mirage Arcane just seems too broken. Given that it affects up to 1 square mile of terrain (27.8 million square feet, or 3/4 the size of Central Park) you can make massive edits. Not only does this have extremely powerful offensive capabilities (due to the fairly loose wording of the spell), it can bypass puzzles and tricks entirely. As the spell itself suggests, you can turn a precipice into a gentle slope. If that’s the limit of the “general shape” wording, you could create an entire valley in the center of a city, as long as the ground isn’t changing more than a precipice to a slope. If the city/town could fit inside a square mile, you can just eliminate an entire settlement or small city with one spell. To use this example again, if you were laying siege to Waterdeep, you could extend the water a square mile inland. That would cut a massive trench through the city and kill a lot of people. You could even bypass things like puzzle doors by cutting the ground right out from under them. The applications are too powerful.

      • D. Walker says:

        The spells you cite all share the same problem that Mirage Arcane does – they are manipulating matter and energy, instead of manipulating the mind.

        They don’t somehow prove that Illusion magic can affect reality – they simply reveal the degree of ineptitude at work on the part of the spell’s author, as the spells have been woefully miscategorized by someone who doesn’t understand the basic logic underlying their own rulings.


        You quote it yourself – Illusion magic “dazzles the senses, befuddles the mind, and tricks even the wisest folk”. Illusions fool people into thinking something is one way, when the reality is that it is another way.

        How, then, does it make any sense for illusion to ACTUALLY change reality?


        Illusion spells are essentially camouflage spells. If you make a door invisible, the door doesn’t stop being a door – it just doesn’t LOOK like a door anymore, but rather empty air. If you try to walk through what looks like empty air, you will smack into the very real door lurking “beneath” the illusion, and you will realize you’ve walked into a barrier of some kind that you can’t see. If you throw a rock, it hits the door and falls to the ground. Etc.

        But if you actually remove the door temporarily, and people can walk through it or throw stones through it without hitting it, that’s clearly not an illusion!

        You aren’t “dazzling the senses”, “befuddling the mind”, or tricking someone! You’re literally altering reality itself and turning the actual physical door into empty air briefly! That’s clearly some form of transmutation!

        • D. Walker says:

          Addendum – I wrote “they are manipulating matter and energy, instead of manipulating the mind”. This is not technically correct!

          Enchantment spells manipulate the minds of targets and make creatures think things are different than they are in reality; but illusion spells effectively manipulate light, sound, smell, etc, and mask reality under some kind of false appearance.

          If you cast an illusion to make the ground look like a pit, it’s like one of those clever forced perspective paintings, except it works from any angle. Anyone who -looks- at the ground will -see- a pit. But if you try to jump in the pit, or throw a rock into it, the illusion becomes obvious, since the ground is still there, it just doesn’t -look- like it is.

          If you instead cast an enchantment one someone, you make that person THINK the ground is a pit, even though it looks normal to everyone else. If the enchanted person tries to jump in, they will THINK they have fallen into a pit, and may even take psychic damage from that, but they will in reality have just fallen over on the ground for no reason. Everyone else looking at the ground will see ground, whereas an illusion would make the ground look like a pit to everyone, and would become obvious to everyone as soon as someone touched it.

          And if you instead cast a spell that turns the ground into an ACTUAL PIT for a while, and people can ACTUALLY FALL INTO IT, that’s clearly a form of transmutation, no matter what Jeremy Crawford or anyone else says. Not all transmutation is permanent – plenty of it is temporary.

        • John Preis says:

          Not all illusions are wholly insubstantial, nor are they phantasms of the mind; some are effective chimerical workings that, as noted, superimpose a degree of reality onto the world… albeit not lasting in existence, but still of substantial effect. This concept has been in DnD since ADnD, and represents a calling forth of (S)hadow essence and/or chimerical quasi-reality. You are only taking into account half of what the Illusion school does/can do — similar to saying, for cross-comparison, that the school of Necromancy can only result in expressions of necrotic energy that destroys things (which it does) or in the animation of undead (which it does also)… but not noting that it can also result in the restoration of true life (which it can also do), which is the opposite in nature to what it’s other qualities represent. Same thing with Illusion: it very often manipulates senses, or creates insubstantial-if-still-very-convincing-appearances… but that’s not *all* it does. The essence of shadow and chimerical forces also are a part of the Illusion school, as well, just as the restoration of true life is a part of Necromancy.

  2. People who climb to the roof of an illusory house that vanishes would also fall and take damage. Illusions so long as you can see them always take the place of a real thing, be it water, air, wood, flesh, metal, rock or dirt.

    If after the illusion spell was done the ground was still a crevasse then yeah I would agree on it being transmutation. Like how an item affected by mending remains mended after the spells duration has passed.

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