I'll be honest, it took me a reread or two to appreciate this story. Not only do I prefer Northwest Smith's adventures to Jirel's, overcoming the current fashion in writing mechanics creates a hurdle as well. Spending so much time in Jirel's thoughts, such as at the beginning of the story, is considered a literary sin as of late, and, like many a maxim, it's one that I absorbed uncritically from other writers. But fashion changes, and, like Kipling's "nine and sixty ways of constructing tribal lays", what may be out of favor might be right for the story. As "Black God's Shadow" is a direct sequel to the earlier "Black God's Kiss", C. L. Moore had to reintroduce Jirel and the events of "Kiss" so that readers would understand why Jirel would risk hell once again to free Guillaume's soul. By presenting this from Jirel's point of view, it explains her motives in a manner less clunky than the encyclopedia-style introduction to "Shambleau". It's also a reminder to modern readers, such as myself, to put prejudices aside when reading. Styles change.
Jirel's journey through hell reminds me of Arizona, where even the plants want to kill you. Her clashes with the dark god are close-run things every time, and Guillaume's soul is gradually pried free from its grasp as Jirel's victories mount. She is an equal to the dark god, never its superior, and she makes mistakes in the battles that, if the dark god were a little quicker to act on, would have led to her defeat.
The ending could have so easily gone for the fairy tale "let this not have happened" resolution, with Guillaume returning to life and Jirel finding love. Instead, C. L. Moore chose to have Jirel make things right. As a side-effect of the curse that slayed him, Guillaume is prevented from going to his soul's fate by the dark god. Jirel never seeks to undo the choice that slayed Guillaume, but is resolute in undoing the injustice caused by her own hand.
All in all, "Black God's Shadow" might not be my favorite in this collection, but its place as one of the more celebrated tales in C. L. Moore's bibliography is deserved.
And something in Jirel knew warmly that the image of life as a tiny spark flickering out in limitless black was a false one— that without light there can be no darkness— that death and life are interdependent, one upon the other. And that she, armoured in the warmth of her aliveness, was the black god’s equal, and a worthy foe. It was an even struggle. She called up the forces of life within her, feeling them hurled against the darkness, beating strongly upon the cold and silence of oblivion.
-"Black God's Shadow", C. L. Moore.