In which book does the War of the Seven Spheres take place?

Question

Somewhere before the Midnight Sons take over and massacre the Dr. Strange Comic Arts, we see a mention of the War of the Seven Spheres. However, what actually happened and how is it not seen? Instead, we directly see a weary Dr. Strange returning to Earth and mentioning that it happened. In which book is the war depicted?

Answer 1

Marvel Crossovers gives a brief summary of the events leading up to the war.

Doctor Strange has been using magic in the name of varies mystical beings over the years (such as Cyttorak, the Raggadorr, Munnopor, etc), calling upon their power to assist him in his role as Sorcerer Supreme. So he must owe them pretty big, right? Well, he doesn't see it that way. When the Vishanti ask for his help in fighting a 5000 year magic war, Strange decides to go AWOL. But that doesn't come without consequences...

And identifies the following comics as being integral to understanding this event (along with a reading order)

• Doctor Strange: Sorcerer Supreme Annual #2
• Doctor Strange: Sorcerer Supreme #42
• Silver Surfer #67
• Doctor Strange: Sorcerer Supreme #43-47
• Darkhold #3-7
• Doctor Strange: Sorcerer Supreme #48-50

Answer 2

The War of the Seven Spheres was a major conflict in the magic community that involved most of the major wielders of magic in the Marvel universe. It was a predestined cyclical conflict among powers and mystic principalities of the mystic planes. In this war, many of the ancient treaties and arrangements between the deities are annulled. As a result, the laws of magic are subject to revision and at times can be circumvented.

The war began in Secret Defenders #25 in January 1995 and ended in July the same year in Doctor Strange, Sorcerer Supreme #80.