This Polygon guide details how to locate all collectible skulls and the terminal in the "Two Betrayals" mission of Halo: Campaign Evolved, the remastered version of Halo: Combat Evolved. The mission follows "The Library" and marks a turning point in the story, as the AI companion Guilty Spark turns hostile, sending players outside the control centre to destroy pulse generators while dodging a three-way battle between Covenant, Flood and Sentinel forces.

The guide identifies four collectibles: the "Alone" terminal, found after defeating four sentinels near the mission's start; the "Tough Luck" skull, reached by commandeering a banshee to fly to a Forerunner structure marked by a vertical blue light beam; the "Black Eye" skull, hidden among Flood growths near the first pulse generator; and the "Mythic" skull, found by flying a banshee to a platform and using consoles to unlock a further area. Each skull alters gameplay when active, such as making enemies more aggressive or boosting their health.