For when obstacles, enemies, and the like are destroyed in game. I'm sure we can use it for a lot of things.
Kind of a different way of animating. I'm used to using outlines or otherwise clearly defined shapes for the most part, but drawing something nebulous like smoke over several frames was sort of a new exercise. As long as the general shapes are consistent it seems to flow well enough though.
Before starting this I had to ask myself, "What does a 1950s explosion look like?" so I took reference from a scene in Earth vs. the Flying Saucers.