Fulminated mercury.
Edited to add: Sorry, been rewatching old Breaking Bad. You’d have to trick them into chewing it or something, wouldn’t you?
I think the rapid expansion when the transfiguration ends would be enough to set it off.
Well, for the first two of my suggestions, the victim would need to have ingested or inhaled that stuff. So smoke would probably also work. Though I wouldn’t want to be nearby in that scenario.
Fulminated mercury.
Edited to add: Sorry, been rewatching old Breaking Bad. You’d have to trick them into chewing it or something, wouldn’t you?
I think the rapid expansion when the transfiguration ends would be enough to set it off.
Well, for the first two of my suggestions, the victim would need to have ingested or inhaled that stuff. So smoke would probably also work. Though I wouldn’t want to be nearby in that scenario.