The Fate of Siggard

"The Fate of Siggard was a Garwulf's Corner column that was written after it looked like Pocket Books wasn't going to be picking me up for another book, and also after I had outlined a second e-book (the title of which I honestly don't remember) and a novel (titled Angels of Darkness, Soldiers of Light) finishing up the story of the character. So, figuring it wouldn't hurt, I summarized the outlines for both in an installment."

- Robert B. Marks

The Fate of Siggard is the title of an e-book proposed by Robert B. Marks as a followup to Demonsbane.

He wrote a full outline, but it has never been published and as such should not be taken as official Diablo lore.

Overview
Siggard is standing in the ruins of Brennor, having just dispatched the archdemon Assur. The Archangel Tyrael, who has been showing up in disguise every now and then, informs Siggard that his suspicions were correct; Siggard is one of a rare breed, who has so much vitality death cannot touch him. After an epilogue that has Siggard walking off into the sunset in search of the next battle, his sword Guthbreoht (forged by the legendary Velund the Smith) at his side, the e-book ends.

Followups
The Fate of Siggard was to be followed up by a second e-book continuation. Below is a synopsis:

Siggard is drinking some mead. Tyrael steps over to him, and informs him that somehow, somebody has discovered the name of the Lord of Terror, meaning that one of the Prime Evils can now be summoned to the mortal realm. Siggard tracks down an evil wizard and confronts him in his tower, but he is too late. Diablo has been summoned. The Lord of Terror tempts Siggard with the idea of restoring his family (killed by Assur a few centuries past in Demonsbane), and suggests that the angels have been lying to mankind all along; the Sin War was never a conflict between good and evil. At the last minute Siggard resists the temptation, slays the evil wizard, and sends Diablo back to the Burning Hells. Tyrael appears and states that it is just the beginning, but Siggard will have nothing of it. The experience has shaken him to his core, and he needs some time alone.

In addition, Marks had anticipated writing a full length novel after this: Angels of Darkness, Soldiers of Light.