If the Sixth World Companion is about providing a options to make a wide range of Shadowrun characters, Shadow Cast is there to help you explore that range.

The book features twenty character archetypes that go off the beaten path, people like an academic mage, a Dissonant technomancer, or a street doctor.

For each archetype, you get information on how people might get into that line of work, with ideas on how to build skills and attributes for that character. There are also plot hooks for that archetype, quality paths, and advice on playing that archetype.