Forum:Stardust Dragon / Assault Mode, Damage Step

I'm not sure what the technical description of the event is, but this has come up several times in my duels, and I'm not sure how this would resolve.

Ex. Stardust Dragon / Assault Mode attacks face down monster. Face down monster reveals to be Man-Eater Bug. Effect target Stardust Dragon / Assault Mode.

Can Stardust Dragon / Assault Mode negate Man-Eater Bug? If so, is Man-Eater Bug destroyed anyway?