Wiktionary
firesetter
n. One who sets fires; an arsonist.
Usage examples of "firesetter".
Tracking the firesetter by his traces was a waste of time," she growled.
The sleigh stand was probably the one where the firesetter left one pair of boots to burn.
She hoped she would see this firesetter before they burned him, so she would know pure evil if she saw it again.
Was it possible that another firesetter was loose in Kugisko, one with a grudge against Ben, as she once thought?