The X-Men
Moira tests Jean's Phoenix powers while Mastermind causes Jean to hallucinate. Moira discovers Proteus has escaped, and Beast learns the X-Men are alive and alerts them that Moira needs help on Muir Isle.
Collects Giant-Size X-Men #1, X-Men #94-131
Collects The X-Men #125-141, X-Men Annual #4, The Uncanny X-Men #142-143. Includes Proteus, Dark Phoenix Saga, and Days of Future Past — the definitive Claremont/Byrne run.
Collects X-Men #86-100 and Annuals. The end of the original Silver Age run -- Havok, Polaris, the Sentinels, and the series transformation.
Collects The X-Men #125-128, Classic X-Men #32-33, 36. Claremont/Byrne's Proteus Saga -- a reality-warping mutant and Moira's tragic secret.
Collects X-Men #97-138 and Classic X-Men backups. The definitive collection — from the Shi'ar saga through the complete Dark Phoenix Saga with bonus material.