WrestleMania XX qualifies as a CMOA for not only bringing about the return of The Undertaker, but also that of Paul Bearer. Kane, who buried Bikertaker four months earlier at Survivor Series 2003 and had been receiving death threats, is waiting in the ring for his opponent, when all of a sudden, the lights go out. Then, out of the darkness: "OHHHHHHH YEEEEEESSSSSSS!!!"
Paul's 2010 return on SmackDown also qualifies. Too bad about the audience's lackluster reaction, though.