Recon trace is a worthwhile addition. I've used it for some hairy production bugs that don't reproduce locally. Allows you to unobtrusively instrument a running system and echo back function calls with their params, including process targeting if needed.

There are a number of powerful tools for BEAM runtime tracing. I prefer this one because the API is simple enough to commit to memory, and it protects against some common foot guns.

https://ferd.github.io/recon/recon_trace.html