Basic Trope: A scene is edited so that the hero is portrayed to be acting in self defense.
Straight: In the original version of Trope Wars, Bob shoots Alice, the villain. In the special edition of Trope Wars, Alice is badly edited to have shot at Bob first and missed, thus giving Bob justification to kill her.
Exaggerated: Every single bad guy, from the Mooks to the Big Bad, shoots and misses at the hero before they shoot back.
Downplayed: The edit makes the villain seem slightly more of an imminent threat by moving his hand towards what might be a concealed weapon.
Justified: The edit is more consistent with Bob's personality.
Subverted: It seems like Bob is going to give Alice a chance to shoot first, but the moment she moves, Bob shoots her.
Double Subverted: It seems like Bob is going to give Alice a chance to shoot first, but then Bob raises his gun... and hesitates. Alice then shoots, Bob dodges, and then Bob shoots Alice.
Parodied: The justifications given are for "offenses" so minor it amounts to Disproportionate Retribution like "was a bad tipper" or "jaywalked back in 1989".
Zig Zagged: Alice and Bob keep trying to shoot each other and missing. Bob hesitates several times before Alice proves herself to be a threat by trying to shoot someone else, but then Bob shoots her before she can pull the trigger.
Averted: The hero finds the villain and kills them with no hesitation.
Enforced: The writers are worried the audience might lose sympathy for the hero for killing a villain that isn't fighting them.
Lampshaded: "I had to let him shoot first. What would people think of me otherwise?"
Invoked: Bob records the exchange via covert camera, and gives Alice a chance to shoot first before he kills her, making himself look better in the record.
Exploited: The villain knows that their first shot will inexplicably miss and dodges the hero's fire.
Defied: Bob psychologically prepares himself, saying to someone else "The moment I get a clear shot, I'm taking it." He does.
Deconstructed: A hero that blatantly lets someone else take a free shot at them is a hero that will probably end up dead or seriously injured. After all, how many times can you really get lucky?
Reconstructed: Bob sabotages Alice's weapon ahead of time, so he can reassure himself (and others) that had Alice been able to, she would have killed him. This allows him to take the shot without remorse.