Reactor is a graph powered saga runner, usually used to give transaction-like semantics to operations that cross system boundaries. In this talk, we'll show how we can use Reactor's graph-driven asynchrony to shorten start up time for Nerves applications by running migrations, provisioning application secrets and starting OTP applications and processes. We'll start by giving an overview of Reactor and how it is usually used in Elixir applications before moving on to demonstrate working with files and finally demonstrate working with it as a replacement for a standard Nerves application startup.