Hint 1

Black must avoid checkmate.

Hint 2 (a very big hint)

Black's e pawn.

Spoiler

https://www.chess.com/analysis/game/live/122884427351?tab=analysis&move=72

e1=N+ - underpromotion!

Underpromotion is very rare. The key thing is it's a check and a check is a tempo which is a very important concept in chess. Why not a queen? No tempo :( so white has checkmate in 3 starting with Rc8+.

I watched this speed chess game live and the move happened even before I thought about underpromotion. I wonder how long it would have taken me to see it in a slow game.

  • HiImThomasPynchon [des/pair, it/its]
    ·
    1 month ago
    1. Play a Swamp
    2. Pass the turn
    3. In white's end step, tap the Swamp and cast Fatal Push, targeting the opponent's king
    4. Chess pieces have no mana cost, so black wins