For board 4, we can win Qs in dummy and cash 3 rounds of diamonds then finesse the club. It will work when East holds Kc and no more than 3 diamonds or W has singleton K and short diamonds.
just take AD KD (keep insurance) then low club. If east ducks, 12 are cold. If he wins KC and leads H, 12 are cold, if he leads low C it's probably 11 but if West gets his 3 discards on the spades wrong 12 is possible
For board 4, we can win Qs in dummy and cash 3 rounds of diamonds then finesse the club. It will work when East holds Kc and no more than 3 diamonds or W has singleton K and short diamonds.
just take AD KD (keep insurance) then low club. If east ducks, 12 are cold. If he wins KC and leads H, 12 are cold, if he leads low C it's probably 11 but if West gets his 3 discards on the spades wrong 12 is possible