I love the idea of boss battles, but I currently don't use them because they do not function nearly as well as other quiz programs out there such as kahoot and quizlet live. Quizlet live is by far my favorite because of the teamwork component. I use this both as review activity and also as a "lets learn new vocab" activity, which is a very important function that sets quizlet live apart.
I would love to see boss battles become more complex and versatile. I agree with many other previous posts that having one student pop up at a time is not a good way to quiz them because everyone checks out except that one student. But even if it was more like Kahoot and the students all entered an answer each time, it can only really be used as review or an assessment.
Imagining how to combine the best aspects of Classcraft and Quizlet live, I am picturing a "Boss Battle Quest" where students work together in their teams to navigate a special quest. Each objective is a mini-boss battle with one or a small group of questions. Every time they pass an objective, they move on to the next. They each get harder. All teams are racing to get to the end first, or maybe they all must finish and a leaderboard of fastest teams is displayed. It would be cool if the teacher could display the map showing where all the teams are while the game is live. Each objective would randomly pull from a bank of questions at that level. It would be easiest to create it so the teams were all looking at one computer or if all their computers had the same thing. It would be much harder to create but super awesome if each team-member took turns answering a question, and each member needs to answer a question correctly each level before they move on to the next. Instead of a quest, it could be a mountain they are climbing up each level to the big boss at the top, or a castle/dungeon and they are breaking through each level of the defenses.