Facing the same boss over and over again and trying to defeat it can sometimes get tiring. I don't remember which game it was, but I had to defeat a boss over and over again and it kept changing shape. One was more durable, the other one did more damage, etc. But you did it it takes some time but it's worth I guess 😂.
RE: Defeating Sylvanas in the Sanctum / Derrotando a Sylvanas en el Sagrario