Second
The second Siege Perilous, which appeared in Uncanny X-Men #229, was a collapsible extra-dimensional gateway with mystical powers. Appearing as a jeweled, hand-held artifact when inactive, Dazzler used it to view many alternate versions of herself, simply by directing a focused beam of light into it. When opened, the Siege Perilous grew into a large gateway size, and could grow large enough for objects as large as the Master Mold to enter it. Those who passed through the Siege Perilous were judged by mysterious entities and then teleported back to Earth, usually naked and amnesiac, and often substantially transformed in some way. The Siege Perilous featured prominently in the histories of Psylocke, Rogue, Havok and Bastion, among other X-Men characters.
The X-Man Psylocke experienced a precognitive vision in which she and the few other active X-Men at the time (Havok, Dazzler, Colossus, and herself) were slain by the Reavers. Upon teleporting back to their Australian base, the vision was proven true as the Reavers had arrived, and closed in on the weakened heroes. Left with no alternative, Psylocke used her telepathy to convince her teammates to enter the Siege Perilous in order to save their lives. After the X-Men vanished into the crystal, the Reavers brought the artifact to their leader, Donald Pierce, who crushed it with his bare hands.
Read more about this topic: Siege Perilous (comics)