The Elixir of Tybal is the only means of curing King Richard after he has been posined by the witch Scotia. According to The Draracle, it can only be created in the ancient White Tower and reveals it's ingredients through a riddle:
"First, you must butcher the creature whose flesh has never lived. Next, you must see the sweetness of your enemy. Your third ingredient must be collected from the deadly depths. Lastly, you will need powders taken from the heart of your mother. This has been inscribed on a scroll for you."