We scan your recent games, find every endgame where the tablebase says you were winning, and show you the exact move where it slipped. Then you replay it until you can convert.
Here's what a spoiled endgame looks like
You're winning K+Q vs K. You play Qg6?? Stalemate. A dead-won game, drawn in one move. The scan finds every slip like this in your games and lets you replay it against perfect defense.