Katy, your question immediately makes me think of a charming, brilliant and hot-tempered narcissist I had as a boss. He too was an obstruction that couldn’t be avoided or overcome.
So we all took one of two paths (and both in some cases). We learned survival techniques to minimize or go around the problem areas. For example, we learned which subjects would trigger his temper and avoided them. We wouldn’t speak in group meetings for fear of being demolished if he was having a bad day.
But that path lasts only so long because it’s impossible to predict if or when you end up a target. I saw many people fired, demoted or leave under pressure.
The better path is a new job as soon as possible.