If you kill Colossus when he does the laser eye he doesn't stop doing the laser eye.

Basically, I killed the colossus boss who's name starts with a Z and I cant remember it, and when I killed him he did his laser beam. The beam did not stop and eventually covered the entire arena.

Also you can cheese your boss by standing behind his left/your right arm. All his attacks miss you except his one close range slam and hit knife stab.