Source: www.andrewrobson.co.uk 
My three favourite slam tools are the Jacoby 2 NT, splinter bids and Roman Key Card Blackwood. Sometimes they all crop up on the same deal, such as this delightful offering from a duplicate at my Club, showed to me by justifiably excited member Howard Jennings.
- Jacoby – showing a game forcing raise in partner’s spades.
- Singleton (void) club in a slam-interested (ie non-minimum) hand. Splintering into a singleton ace is not ideal but, for me, acceptable.
- Loves the short clubs opposite. 4 NT is Roman Key Card Blackwood.
- Two of “five aces” (incl. K); plus Q.
- Showing all the keycards and asking about kings for the grand slam.
- Playing the Specific Kings Method, this shows K but not the cheaper K [nor K, but that was known from the splinter].
West led his singleton diamond and declarer, Jennings, wisely rose with dummy’s ace (other declarers finessed and lost a quick ruff). He crossed to the ace-queen of spades (carefully retaining dummy’s king) preparing to claim his slam if both opponents followed. However when he saw East discard on the second trump, he refrained from returning to the king, necessarily leaving West’s trump outstanding.
It might appear that declarer must lose two diamond tricks to East’s KJ, but enter the Dummy Reversal. At trick four declarer cashed the ace of clubs. He then crossed to the queen of hearts, ruffed a second club, crossed to the ace of hearts, ruffed a third club and cashed the king of hearts discarding a diamond. We have reached the four-card ending (below) :
Declarer exited with a diamond, West discarding a club and East beating the queen with the king. He next led the jack (best), but West couldn’t throw his last club or declarer could ruff low in dummy, cash the king of spades and table the master club. But when West threw his heart, declarer could ruff low in dummy and peacefully ruff dummy’s last club with his trump, West following. The last trick saw dummy’s king of spades beat West’s jack. 12 tricks and slam made.