Flash paper should be would becould very well be used to simulate sparks or sudden “flashes” for the time of performances
https://www.animenewsnetwork.com/bbs/phpBB2/profile.php?mode=viewprofile&u=1212754
Flash paper can also be used to simulate sparks or unexpected “flashes” in the course of performances. The immediate burn is ideal for timing with track, lights cues, and choreography.