These three hands are from Adventures in Bridge, September 6, 2018.
West (Dummy): ♠42 ♥87 ♦KJ1065 ♣AK42
South (You): ♠K1087 ♥K2 ♦974 ♣10965
North (your partner) opened 1♥. RHO (East) overcalled 1♠. You passed. (Bidding 1NT in competition promises 8-10 HCP.) West bid 2♦ and partner doubled. The double is ambiguous; I took it as a DSIP double—“Do Something Intelligent, Partner.” East passed and you bid 2♥. Now West bid 2♠. Two passes to you, and you brought out the double card. Remember the rules of 2-level penalty doubles—your side has about half the deck in HCPs; you have 4 trumps; you have 2 trump tricks.
You lead the ♥K. When Dummy appears, you note that Declarer must have four hearts to go with her five spades. You are not really interested in ruffing Declarer's heart losers with your good trumps, so you shift to a fourth-best club to guarantee your side gets any minor suit tricks that you have coming to you. Partner plays the ♣Q under Dummy's ♣A. Declarer plays a low spade to her ♠9. You win with the ♠10, and lead another club. The ♣K wins on Dummy and partner's ♣J falls. Declarer now leads a heart from Dummy. Partner rises with the ♥A and puts another heart on the table. You ruff Declarer's the ♥J with your ♠7. You lead the ♦9 (top of nothing) and partner wins the ♦Q.
Partner has a complete count on the hand now. He knows Declarer started with five spades and four hearts. He knows from your fourth-best club that Declarer started with three clubs, and therefore has only a singleton diamond. Partner plays back another heart and you ruff with the ♠8. You play the good the ♣10. Partner ruffs with the ♠Q—yes partner just ruffed your good trick, so he can play his fifth heart and you are now guaranteed a trick with your singleton the ♠K no matter what Declarer does. Congrats to Wirt Gilliam on good counting and good defense! Declarer is down 3.
East (Dummy): ♠QJ104 ♥AJ74 ♦K ♣Q1072
North: ♠K982 ♥Q865 ♦Q76 ♣83
The opponents have sniffed at slam with East opening a club and West bidding spades which are supported. West asks for Key Cards and signs off at 5♠ when partner shows only one Key Card. You lead your fourth-best heart. Declarer calls for the ♥A on Dummy, partner plays the ♥9 (encouraging), and Declarer drops the ♥10. Declarer plays the ♠Q from Dummy and partner plays the ♠3 while Declarer plays the ♠5. Your card?
Your best play is to DUCK the spade. You want to cause havoc with Declarer's transportation and the 4-1 trump break will be difficult for him. If he continues with the ♠J, duck that also. Declarer now has a problem. If he has four club tricks (expect ♣AK in his hand), two diamonds (he has cue-bid the ♦A), the ♥A, then four spade tricks leave him one short of twelve. He need to be able to ruff two hearts in his hand OR two diamonds on Dummy, and he cannot sort things out with the 4-1 spade division.
If you take the ♠K on the first round and return a heart, Declarer can ruff in his hand, go to Dummy with the ♦K and ruff another heart. Then, Declarer cashes the ♠A, returns to Dummy with a club and pulls the remainder of your spades, discarding losing diamonds. He'll take 12 tricks. [The two pairs not in slam actually took 12 tricks. One pair went down two in 5♠ and another was down two in 6♠.]
DON'T BID THE SAME VALUES TWICE!
East fell from grace on Hand #6.
East: ♠A10976 ♥K ♦AQJ10 ♣983
South (Me): ♠KQJ4 ♥J32 ♦K3 ♣J1072
East opened 1♠; I passed; West bid 1NT (forcing) and North (partner) made a lead-directing 2♥ overcall—risky, but I'm a passed partner; we're white against red; and he really wants the lead. East fell from grace by bidding 3♦. She was light a King for that bid—should have reverse values to bid at the 3-level opposite a partner who has only promised 6 HCP—PLUS her the ♥K is useless on offense. West took the “false preference” back to 3♠. That was passed around to me and I brought out the red card. When the dust cleared, they were -1100.