X-Men: Reign of X by Jonathan Hickman #1

This collection kicks off the Dawn of X era with Jonathan Hickman's foundational X-Men work, gathering the opening issues of House of X and Powers of X. It establishes the mutant nation of Krakoa, redefining the status quo for Charles Xavier, Magneto, and a vast ensemble of mutants as they forge a new society. The volume sets the stage for the sprawling narrative that follows across multiple X-titles.