Since the succession of Covid lockdowns put an end to game group meetings here I have been listening to a lot of online rpg sessions via YouTube. Doing so I noticed, then found irritating and have now come to hate the climactic death scene commentaries.
GM "...and he goes down, sinking slowly to his knees, his last faltering breaths wasted, cursing you and your kin. <pause for effect>
...............So tell me what that looks like"
Where the fuck did that come from? Have a whole array of GMs simultaneously adopted the Mercerism "Howd'ya wanna do this?" or is it now supposed to be a required part of the way games are run? One stream I was watching the GM extended it to every critical hit the PCs made.
Speaking for myself, it goes back to the 90's, when there was a 1E vs 2E edition war, where the 2E people wouldn't constantly be painting 1E as a mindless wargame, where the only option was kill, not like all the fancy options in the fighters splatbook for taking people alive. Like 2E actually has a rule for pulling your punch. People felt you couldn't do that without a special rule saying you can. I found myself having to explain the whole "hit points are not all physical" thing which Gary spells out nicely in 1E, and that a logical consequence of that is when you strike someone down to zero hit points, they're basically your bitch at this point. If you don't announce some other intent (like subdual), the assumed/default intent is to kill. But you could opt to do pretty much anything else instead.
Well, if you take that to heart, to the point where players consider their intent on each and every attack, that can burden the game some. So why not worry about intent only after you hit to speed things up. And then why not only after the hit that puts the opponent down to zero. And at that point you're pretty much there. The missing piece is easily inspired by the highly popular video game at the time, Mortal Kombat, and it's like, "Okay, describe your Finish Him."