Semi bluffing means to place a bet on a hand that is not the best at the moment but has real chances for improvement and may become even the strongest on the next streets. A good semi bluff is a very powerful weapon. The only think you need to consider is: if the chance your opponent to fold is really very small, the semi bluff is not the best choice.
For instance, if you play with short stack, you can bet or raise (going all in) on the turn in case you have a strong drawing hand. In other words, you can use the classic semi bluff. For example: If you have an Ace of clubs and a King of clubs, there are Jack of clubs, 5 of diamonds and 6 of spades revealed on the table, the turn is 10 of clubs, there are $ 200 in the pot and you have $ 200 stack as well.
In this case you can absolutely go all-in if you play against one opponent since your winning chances in most cases will be enough for a “positive” call in answer to your opponent’s bet and your attack can make fold many marginal hands which may be stronger than your hand during the showdown if you don’t improve your hand on the river.
In case your opponent has a Jack of diamonds and 9 of diamonds, after your check, he most probably will attack..Then you will be forced to call having 18 outs i.e. 41 % winning chances. In this case:
0, 41 × 400 – 0, 59 × 200 = $ 46
In other words, this call ($ 200) will bring you a profit of $ 46 per hand comparing to a fold.
In case you attack first and your opponent folds, in 15 % of the cases your profit will increase. In 15 cases out of 100 you will win a pot of $ 200 and in the rest 85 hands you will have 41 % winning chances. Your bet in this case should be equal to:
0, 15 × 200 + 0, 85 × (0, 41 × 400 – 0, 59 × 200) = $ 69,1
In other words, the semi bluff bet of $ 200 in this situation will bring you a profit of $ 69 per hand.
Generally, in order to play with drawing hands you need to have a two ended straight and overs i.e. a combination which is at the edge of a “positive” call when the bet is comparable to the size of the pot. To use the semi bluff with weaker hands is not recommended, especially if you are not an experienced player – in this case the semi bluff may become a very dangerous weapon.
Taking into consideration that there is only one card to be revealed, your drawing hand is not to be considered that strong anymore and if you decide to attack with such a hand that will be a pure bluff.
The main philosophy of the turn is as follows: You should continue the attack only with a really good hand. Generally, in order to continue the attack on the turn, you should have an over pair or better, or at least a top pair on the flop with a good kicker. Of course, there are always exceptions. One of these exceptions is a correct semi bluff.
After the situation’s evaluation according to the above mentioned criteria, you should make an important decision: to continue playing or to pass. Knowing the number of your outs, you should calculate how many percent are your hand’s winning chances and how many percent of the pot will be your call. Then you should compare the results. In case you need to put into the pot more than your winning chances, you should fold, otherwise you should call or even raise (in case your winning chances are more than 50 %). For example:
Let’s say that in the above mentioned example the pot is $ 200. This means that you have roughly 31% winning chances:
3 × 9 + 2 × 2 = 31 % (see the calculations above)
The first scenario: your opponent places a bet of $ 150. What do you need to do?
The pot now is $ 350 and if you call, you need to place $ 150 i.e. 3 against 7. This means that your call will be 30 % of the pot and if you have 31 % winning chances, you can call since your winning chances are bigger (not much but bigger anyway). In other words, you should call – you have positive expectations.
The second scenario: your opponent places a bet of $ 200. What do you need to do?
In this case the pot is $ 400 and if you call, you need to place $ 200 into the pot i.e. 1 against 2. This means that your call will be 33 % of the pot and if your winning chances are 31 %, you have negative expectations, therefore you should not call. The best decision in this case is to fold.