This is useful for, for example, triggering different weather conditions. In this example I'll add different types of snow.
This VFX project was an exploration into creating realistic fire which would burn from ignition, through initial burn to a roaring flame and then eventually dying.
Flipbook tool for Unreal Engine - easily make an animated flipbook texture without Adobe After Effects
As an example, say you want to spawn a blueprint actor called BP_FIRE_LOG and give it a unique ID number so that it can be referenced in the level.