I have a question regarding change. I was told that change must always have a duration and that change can not be permanent. This makes no sense to me. Perhaps my understanding is off. If I take an object, any object, and change it using mundane means it stays changed. The duration is how long the change takes.
For all spells, but especially for change and creation spells, the following principle applies:
The duration of a spell is how long the magic lasts. After the duration ends, the other natural laws assert themselves.
Examples:
If you move an object 10 metres into the air, when the magic ends, it will fall down (gravity).
If you move it 10 metres to the left, it will stay there when the magic ends, because there is no force forcing it back to its old position (unless it's on a hill etc - you get what I mean).
If you create an un-natural object, such as summoning a demon, or creating an illusion, it will disappear when the magic ends.
A magically created natural object, like a wall or some coins, will stay after the magic ends.
If you change an object or person into something else in a natural way, the change will be permanent. Example: Healing spells, grooming spells, etc.
Unnatural changes will revert at a "natural" rate. So a 3rd arm will wither and die off, not a pleasant experience. It won't vanish immediately, because that wouldn't be a natural thing, either.
For those spell with a permanent result, duration is not the duration of the change lasting, but the speed of change - the duration during which the change takes place. Don't make instant change spells if you want the target undamaged/unharmed, because the human body and most objects will rupture if you change them too suddenly.
Maybe we should have different intents for these. I think that would make sense. Looks like we have to clean up our intents once we have a full picture.