Newton Comics' The Amazing Spider-Man #12 was published 8 November 1975:
The cover is modified from the original appearing on the cover of Marvel's The Amazing Spider-Man #11:
According to the GCD entry the image on the cover of The Amazing Spider-Man #11 was modified by Jack Kirby and flipped. The original image, "taken from an unaltered stat", was later printed on the cover of Marvel Tales #148:
The modified image on Newton's The Amazing Spider-Man #12 previously appeared on the cover of Pow! #24:
The GCD entry for this issue references Kirby alterations to the face and legs of Doctor Octopus, as does the entry on Marvel's The Amazing Spider-Man #11, but clearly the glassless version on the Odhams and Newton editions is yet another variant.
The story contents are as follows:
Turning Point, originally published in The Amazing Spider-Man #11, April 1964
Defying the Magic of... Mad Merlin!, originally published in Journey into Mystery #96, September 1963
Only the first 7 pages of the Thor story are reprinted. The story is continued in the following issue.
The Ghost Rider poster is from the cover of Ghost Rider #2:
The expiry date for the competition is 22 December 1975.