The Ritual is a Document in the Rise of the Tomb Raider: 20 Year Celebration DLC Blood Ties. It belongs to the Lord Croft's Journals set and contains the description of the failed attempt of Lara's father to resurrect his wife Amelia with an ancient Tibetan ritual.
And it has failed, there is no doubt in that. I prepared everything according to my research. When I dropped the stone into the elixir and held it to her lips, I thought, for the barest moment, that it had worked. The hour was midnight, and my pocket watch stopped inexplicably... there was a charge in the air, like the moment before a lightning strike.
For a heartbeat, I imagined that my life was being drawn from me as one empties a glass, in order to be poured back into Amelia. I would have welcomed death if the last thing I saw were her eyes, clear and alive again.But the moment passed. Amelia is still dead, and I was nor Opheus. We will return to the manor, and lay her to rest. I owe her that much.