I'm fairly new to tabletop RPGs and recently I've been GMing more. I'm curious about how various GMs handle rollbacks (or whatever they might be called in TRPGs); situations where you realize you did something wrong and roll back to an earlier point.
I was running a one-shot and one of my characters (paladin) was possessed by an evil tome. Another character (wizard) tried to take it from her and she attacked him. He had 11 hp left, and she rolled her damage: 1d10+1, and of course she rolled a 10. This was Dungeon World so I had him roll Last Breath, which he failed. I declared that the paladin's slash was so mighty that she cleaved his head from his shoulders.