What is the best way to create the illusion of fire without having actual flames

Question:

What is the best way to create the illusion of fire without having actual flames?

This is for a stage performance in a venue without a fire certificate.

Best Answer - Chosen by Asker: ,.ok time to get out your red,.,.yellow,.orange,.markers or crayons and start scribbling like you did in kindergarden,,.,,.,.

good luck,.,. thanks,..,