Hit the level cap?
Run out of dungeons to do?
Raiding is the next step and an option you can exercise. It involves coordinating the efforts of much more than 5 people as they fight their way through epic sized bosses. The strategy is often more complex and involved. You won’t find just advice on raiding bosses here. Look at raiding from an activity and management standpoint. There will be times when you are at your breaking point. Being able to manage your raid group’s expectations and abilities is a crucial skill to possess.