Deadpool #3 Secret Invasion 2008

Deadpool #3 from 1997, written by Joe Kelly with art by Ed McGuinness, sees Wade Wilson's regenerative healing factor inexplicably failing. After a taunting package from Black Tom Cassidy, Deadpool's teleporter is hidden by Blind Al, forcing him to seek out Siryn. Their quest leads them to Doctor Killebrew in the Swiss Alps, who reveals a dire truth: Deadpool's entire body is dying. This issue is a significant part of the early, character-defining run, exploring Deadpool's origins and the breakdown of his powers.