In a team game, you are declarer in 6♠. West leads a trump and East follows. When you play another round of trumps, both opponents follow. You now have a way to guarantee your contract. Do you see it?
Declarer (South) has 11 top tricks, and the easiest way to score a 12th is simply to ruff a heart in the closed hand. After winning the trump lead, declarer plays another round of trumps, both defenders following. After the last trump is drawn, the heart finesse is taken for a possible overtrick. Depending on whether the ♥K is onside, declarer will next play the ♥A and ruff a heart in his hand for 12 or 13 tricks.
♥ A Q
♦ K 10 5
♥ 5 4
♦ A J 2