Partially it depends on the difference in size between the base materials and the target form. Things can be Transfigured smaller (Harry’s father’s rock to tiny diamond) or bigger (ice cube to rocket). The rock reverting could tear Harry’s hand off, conceivably- shards of metal (or rust) getting significantly bigger or smaller once inside your body seems likely to be uncomfortable.
That would make for a pretty nasty situation. I had considered throwing a large rock that was transfigured to be smaller, then dropping the transfiguration in the air. This would be even nastier (though maybe not as effective): transfigure a large rock into a needle and throw it at them, then when it’s inside them reverse the transfiguration.
Partially it depends on the difference in size between the base materials and the target form. Things can be Transfigured smaller (Harry’s father’s rock to tiny diamond) or bigger (ice cube to rocket). The rock reverting could tear Harry’s hand off, conceivably- shards of metal (or rust) getting significantly bigger or smaller once inside your body seems likely to be uncomfortable.
That would make for a pretty nasty situation. I had considered throwing a large rock that was transfigured to be smaller, then dropping the transfiguration in the air. This would be even nastier (though maybe not as effective): transfigure a large rock into a needle and throw it at them, then when it’s inside them reverse the transfiguration.
Huh. I wonder how that interacts with conservation of momentum. (Or if it does.)
I think if you can Transfigure an ice cube into a solid-fuel rocket conservation of momentum is the least of your concerns.
Which is easier: “Become a solid-fuel rocket, which is shaped like this and this and has these parts...”, or “Smaller, please.”
Probably cheerfully ignore them, considering magic’s general relationship with physics.