In late 1989 Marvel adjusted their cover dates so that they were only two months ahead of schedule instead of four, hence the "Mid December" cover date. A full month passed between the publication of this issue and the two issues surrounding it.
This issue has variants:
Boom Boom, Warlock, and the Wolf Prince rescue the Warriors Three. Volstagg's children find Balder and Karnilla. Cannonball, Rictor, Sunspot, and Wolfsbane hide in Hela's army. Hela launches her attack. Meanwhile, the Vulture and Rusty escape from prison.
Part 7 of 8. Acts of Vengeance crossover; For a complete checklist of the Acts of Vengeance issues, please see the cover notes for the story Prologue in Avengers Spotlight (Marvel, 1989 series) #26.