Ever since the release of the agile manifesto in 2001, agile methods have received widespread interest in industry and academia. Agile methods have transformed and brought unique changes to software development practices by strongly emphasizing team collaboration, change tolerance, and active customer involvement. Their proven benefits have also inspired organizations to apply them in large-scale settings. However, the adoption of agile methods at scale entails unique challenges such as coordinating and aligning multiple large-scale agile activities, dealing with internal silos, and establishing an agile culture & mindset throughout the organization. In particular, agile coaches and scrum masters are confronted with unprecedented concerns in large-scale agile development. Notwithstanding their importance for large-scale agile endeavors, extant literature still lacks an overview of their typical concerns and a collection of patterns to address them. Against this backdrop, we provide an overview of typical concerns and present five best practices of agile coaches and scrum masters in large-scale agile development.