Consisting of Beneath the Vaulted Hills and The Compass of the Soul, by Sean Russell. Contains voyeurism and probably some other objectionable things.
Another fantasy, of course, set in a world where mysterious Strangers occasionally appear, lost through holes where the worlds touch together. The mysterious Lord Eldrich is the last mage remaining and is on a terrible and ruthless mission to carry out the charge left to him: eliminate magic from the world lest a terrible apocalypse foreseen 500 years before be unleashed upon the world.
Eldrich would have had little problem finishing out his quest but for a rebel group called the Tellerites who are determined to see that the power of the mages is not lost. Their hope is placed in Anna Fielding, trained to be a mage but unable to become one without the jealously guarded flower known as king's blood, a powerful and habituating herb that enhances magical power...
In almost every way, Eldrich is a terrible foe, dealing ruthlessly with n0t only those who oppose him but almost anyone involved at all in order to destroy Anna and the Tellerites, but, especially in the second book, the more human side of him is shown: he is not an exceptional mage, only the last one, and he is terrified that he will be unable to carry out his duty.
The ending was not very satisfying to me, but perhaps inevitable. The rest of the story was fairly compelling, although the frequent switches to different sets of characters in each chapter was somewhat distracting and possibly detracted, as the author may have tried to detail too many characters and as a result leave several unfinished.