General raid mechanics[]
Raid bosses are special bosses that can spawn when you use AP on main story or event story stages. The more AP you use in the stage, the better the probability of spawning a raid boss. When the boss spawns after a stage, you're given the option to go fight the boss alone or request for help, or you can continue with your story/event.
Going to fight the boss gives you two options, head into battle or request for help. Requesting for help gives other players the chance to contribute in killing the boss you spawned. Whether or not you request for help, going into battle with the boss does not cost you AP and takes you to a special stage with only one wave with the boss and two minions on the side.
To win the fight, you don't have to kill the minions the boss spawns with, just the boss. The minions can contribute to you taking damage or getting hit with status effects, so keep that in mind. The boss itself has a big health bar with several lines on it indicating certain HP thresholds. A normal version of the boss has fewer and less health for its respective level while a badass version with a glowing aura has more HP threshold markers. Once you take the HP of the boss to below these markers, the boss will instantly gain its action gauge full and take a turn regardless of where their action gauge was before. Some raid bosses have special attacks at specific thresholds that will trigger.
Once you kill the boss or participate in killing it yourself, its level will increase, spawning a tougher level boss unless you hit the raid boss level cap. The normal and badass boss versions level separately from each other. If you give up on the boss instead, its level will drop. Requesting for help and not fighting the boss yourself at all will keep the level of the raid boss the same when it spawns the next time. This will help you get raid points even if you can't kill the raid boss at its cap. Getting friends to kill the boss in your stead will keep a consistent flow of points coming your way, although note that new friends will not receive your call for help if you sent it before adding them to your list. Participating in other people's bosses also nets you half points of finding a boss as participation reward, so it's recommended to participate in assisting against bosses even if you can't kill them.