There are some unique bits too. Phoenix Channels is a beautiful, shit-simple pub/sub abstraction on WebSockets and provides both JS and Elixir libraries. And then came Phoenix Presence, which can track shared state (like a user's online status) in a durable and fault-tolerant way.
Both are useful libraries, but the fact that they work in server clusters as well as single-node deployments is the real kicker. That's just how Erlang rolls.
