The level would start off as you face to face with Reggie, who's not unlike Guts Dozer or Apocalypse from X-Men VS Street Fighter. But the more you shoot him, the larger he gets, and he eventually becomes the stage itself.
When you eventually deplete his life energy (if such a thing in nature is possible), the stage explodes, kills Mega Man in the familiar death ball explosion animation, and normal Reggie is revealed.
The scene ends with one remark by Reggie, "Not my problem."