Programming boss-level enemies that are challenging by themselves is rarely done right, as they usually serve as big bullet sponges that deal high levels of damage and have a bunch of normal enemies surrounding them to help in the process of killing you. Destiny, unfortunately, chooses not to make simply challenging boss battles, and elects for this more arduous, drawn out route. This problem has yet to be remedied, and remains a consistent consequence of raising that difficulty before starting a mission. This occurs far too often throughout many different story missions and raids. What Bungie has continually failed to recognize with this boss design is that a tremendously infallible health bar isn't what's supposed to make a boss challenging. It's all about making a battle strategic, learning patterns of attack and using developed skills to defeat them. When you remove the fun of boss fights, you remove one of the greatest aspects of other RPG's, leading to a further disconnect with the enjoyable aspects of your playing experience. Bungie have taken the too easy route of making the higher level boss battles being tests of patience and duration. The player shoots and shoots, until the boss is finally defeated, leaving the player happy that it didn't last any longer.