The Adventures of the X-Men #4

Cyclops returns from a day off to find the city of Salem Center overrun by N'Garai demons. He finds out from Erich Zann (the latest in a long line of protectors of The Dweller in the Darkness) that \"The Dweller in Darkness\" has been summoned and will destroy the Earth. It can only be stopped by reading the counter-spell found in the Book R'lyeh, however, this will send both the reader and the demons back to the N'Garai dimension. Cyclops recovers the book and Erich, wishing to atone for the sins of his family, reads the counter-spell and saves the day.