Phantom is the penultimate book in the epically long Sword of Truth series by Terry Goodkind.  The plot of the previous book, Chainfire, is continued and expanded upon in the tenth book of the series.

Phantom continues Richard’s search for his missing wife, Kahlan.  The Chainfire spell discovered in the previous book is still in effect, but Richard discovers that the spell form has been corrupted, as has all magic to some extent.  At the same time, Richard sees that the direct confrontation battles between the New World and the Old World are futile, since the Old World has supplies and troops far beyond those of the New World.  Richard orders his army to break into multiple, small armies, and sends them into the Old World to wreak havoc and destruction.  Meanwhile, Kahlan, having no memory of who she is, travels with the Sisters of the Dark to gather the items needed to cast an all-powerful magic that would give the Sisters immortality and unparalleled power.

-[insert revolutionary thinking here]