The Dream Time is one of the Documents in Baba Yaga: The Temple of the Witch (additional content for Rise of the Tomb Raider). These are messages Lara Croft records upon the discovery of certain base camps.
I can't make sense of what I experienced in there...
I don't have the words to describe what I just saw. I went inside the Wicked Vale, looking for Nadia's Grandfather, but I barely escaped with my life. It was like... a fairy tale, but through a broken, filthy mirror. And... Dad... I know, intellectually, it was all in my mind, but... the gunshot is still ringing in my ears. There's something terrible going on in there, and while I don't believe that it is magic, it is... extraordinary. I have to find out what's behind all this, but first, I have to find a way to see clearly...