Berkley Medalion November 1976 paperback (D3260; Berkley-Putnam hardcover was earlier the same year..) Cover by Paul Lehr, 220 pages, $1.50 cover price. Condition is Fine: tight and square with flat spine; age tanning is very mild (much better than expected for its age.) No stamps, marks or writing - a very clean copy that looks new/unread.

The Powers of Blackness - a fix-up built from 5 novelets with little or no changes to the source material / first time in a Williamson collection. The 5 sections of the book (labelled 1 to 5) correspond to:
1. =(The Power of Blackness)
2. =(Counterkill)
3. =(The Machines That Ate Too Much)
4. =(The Eternity Engine)
5. =(The Dark Destroyer)

These are from 1973 to 1976 - the first 3 are from Magazine of F&SF, then Galaxy, and the last from Amazing.