AdMobius is a mobile audience management platform that uses Cascading for complex data aggregation and processing in its tech stack. Cascading allows AdMobius to easily write custom aggregators and workflows for tasks like device graph building, scoring, and profiling audiences at scale across billions of mobile devices. Some key benefits of using Cascading include its support for custom joins, taps for various data sources, and best practices like checkpointing and compression to optimize performance.