End game trigger question

[MunchkinMan]

The timing in Munchkin is simple: You play a card and deal with its results immediately. There is no "stack," and only cards which say they can retroactively cancel something (Wishing Ring is always the best example, in that it can be played to react to something). There is also only one portion of the game where people are given reasonable time to play cards to prevent something, and that's during the combat, not after the fact. In other words, the time to stop a Cowboy with a Steed from winning the game at Level 9 was while he was giving everyone a chance to stop him from killing the Monster(s) that let him get to Level 9. Once he's won the combat and the game that way, there's no, "Oh, whoops, I forgot to look at your cards and make sure I understood what was happening. You don't have the Steed now though, so you didn't win."

Now, if he was in any way keeping his "about to win" status surreptitious, as in trying to hide that he was a Cowboy and had a Steed, I'd consider making sure players announce that they're going to win the game.