There are lots of myths about the viva: they’re impossible to really prepare for, they’re unfair, unknowable, harsh, a hazing, and not that fun.
There is lots that is true about the viva: the vast majority of people pass, regulations and expectations can be found out quite easily, preparation is possible, examiners don’t aim to be harsh – and a viva might not always be fun but it’s usually fine.
Myths circulate among PGR (candidate) communities. The truth is known in PhD (graduate) circles.
You have to ask the right people to find out the truth about the viva.