Lendon Bracewell Covers the Basics for Working With Multichannel EXR files in After Effects.
Once upon a time, a composite in After Effects used a lot more assets, but that all changed when EXR came on board. Eventually, Ae users were able to work with the high-end file formats used by the VFX industry as a standard. The high dynamic-range images provided extensive color, but also the ability to embed multiple channels. Way more channels than RGB+A. Multichannel EXR files can contain all the render passes that you need for compositing tasks, in a tidy single file. EXR stuff in After Effects is possible through Fnord’s OpenEXR plugins that come bundled with Ae.
Showing how that all works within After Effects is Lendon Bracewell from Action VFX. Bracewell shows how you can composite some VFX elements using a multichannel EXR that contains valued depth information, a pass that you can use to change the lighting, and some matte passes to make it all come together.
Lendon uses some assets from the Action VFX Ground Burst collection that has 14 Ground Burst elements at various angles with all the elements staying entirely within the frame.