List of things Sona does:
Use dj equipment
Say deep stuff such as "dsadsafasd" which means "dsadsafasd"
Only allow her summoner to hear her saying "dsadsafasd"
List of things Garen does:
Not Let the Glory of Demacia ever fade!
Lead the Charge!
Protect their land!
Carry a lot of weight on his shoulders!
Hold the World up!
Also keep in mind you can clearly understand what he is saying, even if you are playing League of Legends with one hand as you probably are fapping to Rainbow Dash hentai while playing Pony mating call in the background, which is what most DJ Sona fans do in their free time anyway.