Raymarched Aurora Borealis implemented as a full screen post-process effect for Unreal 4. Fully volumetric, and can reflect some light on the ground as well.
Written in hlsl, masks created using Substance Designer. Has a bunch of parameters to achieve different looks!
Available on GitHub for UE4.26: https://github.com/Hideous/UE4-AuroraEffect
Background landscape is from the Brushify Arctic pack, used for demonstration purposes.