In the GenCon Edition of The Sixth World Tarot booklet, there is a reference to a "third Tarot spread" and it is called "The Tree of Life Spread".
There is no Shadowrun "Tree of Life Spread" and it was an error to include it. There is a common "Tree of Life Spread" that some who read Tarot cards may use, but that is not the one the booklet was intended to refer to. A "third Tarot spread" was never actually developed.
Sorry for the confusion. Hopefully that errata was corrected in the upcoming actual release of The Sixth World Tarot.
