It’s some deep Eldritch magicks that Jeffe and Anttix conjured up that will auto-build Marlin based on certain config files. If a certain configuration is deemed popular or common enough, it could be blessed, and get an auto-build config. Then, anytime they pull the newest build from Marlin, or apply a custom patch while waiting for a PR to go through, it will automagically rebuild Marlin for all the configurations.