Why are you just standing there? She's totally going to kick your ass when she's done transforming. Oooooh! You're doing that thing where you're being uncharacteristically chivalrous even though you just murdered her entire defenseless family for some cheap laughs. Well, it's your funeral, buddy. This is where a villain, usually, will obligingly wait for the hero to finish his transformation before proceeding to bloody murder. This is separate from a Transformation Sequence in that while the sequence can be ignored, in this case it IS ignored. Villains may have several reasons for doing this.