The following is from a new book Jonathan Little is working on called Jonathan Little on Live No-Limit Hold’em Cash Games.
A semibluff is a bluff made with a hand that’s usually beat at the moment but has the potential to become the best hand in the future. The most obvious example of this is when you raise the flop or the turn with a flush or straight draw. If your opponent raises and you call with 
and the flop comes 
, and your opponent bets, raising is a strong option because any spade, seven or deuce will frequently give you the best hand. Notice if you call, you have to hit your hand to win, but if you raise, you can win by making your opponent fold a better hand or by completing your draw. Having two ways to win is usually better than one.
It’s important to think about your implied odds and overall range when making a semibluff because you do not want your opponent to know you have mostly draws in your range. This is why you often see good players raising the board with sets, two pairs, strong top pairs and draws.
This puts opponents in difficult situations because they have no way of knowing if they’re against a premium made hand or a draw. Either way, they’re in rough shape with a hand like K-Q. If you can frequently put your opponent in awful situations with hands as strong as top pair, you will find most of the small pots being pushed your direction.
Semibluffs vary in strength and potential. In general, the fewer outs you have, the more your implied odds tend to be because your draw is less visible. Suppose someone raises and you call with 
on the button.
The flop comes 
. If your opponent bets, raising is an excellent play. If your opponent calls and the turn is a diamond, queen or seven, your opponent will often assume you hit your “obvious” straight or flush, allowing you to win the pot with a turn bet. If a 10 comes, your opponent will assume you missed your draw, allowing you to get paid off when you make the nuts.
Also, if a queen or jack comes, you will have a decent top pair that will tend to have some value. Notice you will get your opponent to fold with a turn bet when the draws you don’t have arrive and you have a decent shot at getting paid off when you hit, making this an ideal semibluff situation even though you only have a gutshot with overcards on a scary board.
On boards that tend to be less draw heavy, hands like bottom pair become decent semibluff candidates. Suppose someone raises, someone calls and you call with 
on the button. The flop comes 
. If the first player bets and the other player calls or folds, you have a reasonable semibluff situation.
If the continuation bettor has a jack, he will have to worry about the caller or you having him beat. The caller will usually have a marginal made hand and will likely fold to your aggression. Notice if one of your opponents calls with one pair, you have a decent chance of improving and you can also win the pot with an additional bet on some turn cards. Realize that any club, eight, seven, three or deuce gives you an additional semibluff opportunity on the turn.
— Jonathan Little, a representative for Blue Shark Optics, is the author of Professional Tournament Poker Vols. 1-3, owns the poker training site FloatTheTurn.com and 3bet Clothing, plus check out his iPhone app, Instapoker.
