I’m a DM. I have players (as many of us do) who sometimes don't do what I expect (as many of us do). Which brings me to Balasar, the Dragonborn Warrior, who is not very bright.
Balasar decided that the best way to get an Orc army out of the way was to challenge their leader to combat. So far, this was largely what I had planned for.
Then Balasar went off script. He charged the Orcish army BY HIMSELF and challenged the Orc Leader to SINGLE COMBAT! This was a boss that was designed for at least three players.
So as Balasar tried to solo the boss, I gritted my teeth and prepared for player character death. Always fun.