From Hard Drop  Tetris Wiki
This is an opening created by player Mr. TSpin. STD stands for Single Triple Double which notes how many lines are cleared by the corresponding TSpins. It is efficient in the sense that it does not waste any T's, the rate of success is extremely high, and that it starts the B2B early. It is also a good way to counter Center 4Wide openings.
Contents 
Mr. TSpin's SingleTripleDouble









Mirrored Alternative to Mr TSpin's STD
In the event that you get a late J, consider this:

OSZ in Second Bag
The O, S and Zpieces in the second bag can always be stacked in a way that a TSpin Triple is prepared at the end of the bag. The order of the pieces in the second bag does not matter at all  the stack will always look the same at the beginning of the third bag.




Perfect Clear chance
If Jpiece comes late in the second bag, then the positions of Opiece and Jpiece can be swapped that means the Opiece is used to build the overhang. This results in a small Perfect Clear chance after 8 cleared lines (3 bags) whereas only a TSpin Single is made in the third bag.





Here are some further patterns to achieve the Perfect Clear. One of those 6 patterns will be applicable for 39.3 % of all third bags.





Nosomi Continuation
Like previously mentioned, the stack will always look the same after 2 placed bags. With this continuation discovered by the player Nosomi, even the third bag can be placed in the same way, whereas a TSpin Single is made in the third bag instead of the usual TSpin Double. The Zpiece stays on hold until the end of the bag and is then used to prepare a DT Cannon. Altogether, the following TSpins are made in the first 5 bags:
Single > Triple > Single > Double > Triple.






Disadvantage of the technique is that you may have to softdrop the Opiece during the third bag; or make a tricky twist to get the Tpiece in place, if the Spiece was already placed: First you rotate by 180 degrees, then you softdrop a row, rotate in an arbitrary direction (the T piece will be kicked) and rotate back in the other direction.






Here are some alternative ways how to place the fourth bag:



STSD
First Setup
You can also do an STSD with a 58.3% chance to end with a Perfect Clear after 14 lines.





Here are all solutions. The first 3 may result with a TSpin Double beforehand.





You can also stack the fourth bag this way. You will only need L before S and O:




If you abandon the STSD, then there is a chance of a PC after 10 lines.





Second Setup
There is also another way to set up an STSD which could end with up to 100% chance of getting a 14th row Perfect Clear. This setup was discovered by the player CaptainCream.



In the third bag, the S, J, L and I on the 3rd bag can be stacked in one of the following three ways:



If L comes before O on the 4th bag, making the first 4th bag pattern is possible. This pattern has 93.23% chance of Perfect Clear. If T comes first on the 5th bag, the chance increases to 100%. There is also a slight chance that TSpin Double, Tetris and Perfect Clear could be done in the same bag.
16 solutions; 7 are shown (Both TSpin Double and Tetris could be done on the second Perfect Clear pattern). All solutions.







If O comes before L on the 4th bag, making the second 4th bag pattern is possible. This pattern has 76.51% chance of Perfect Clear. All solutions.
8 solutions; 4 shown




Other TSpin Single Triple Double Openings
Mr TSpin Analogon
Left and right part swapped, so the TSpin Triple overhang points towards the wall. This opening has the same dependencies as Mr. TSpin's STD in the first bag (must place O before I and Z before L), and in the second bag O, S and Z must be stacked in the same way. After the execution, the only real difference is that the TSpin Triple overhang points towards the closer wall which will result in different leftovers.


If I piece comes last in first bag, one can also drop it on the wall which allows to stack the TSpin Triple overhang differently.


Here are some ways how the second bag can be stacked, if the I piece is placed in its usual spot. None of them result in a Perfect Clear chance.






To prevent that vertical Lpiece overhang, it is sometimes possible to keep the L piece on hold and use Jpiece from the third bag in its place.


Pokemino's STD
Almost every game can be started with this opening. The only dependency in the first bag is that J must be placed before Z (respectively L before S in the mirrored setup). In contrast to Mr. TSpin's STD it is not possible to make a TSpin Triple at the end of the second bag every time. The dependency is quite high in the second bag, that I must come before Z and O must come before J.


In the likely case that the overhang cannot be completed with the second bag, the following stack is well suited for most third bags.




Hopefully, S or Z show up before T in third bag, so that no T piece must be wasted. Otherwise, it is also possible to spin in the Tpiece to get a TSpin Double, then stack an overhang on the left side to make a TSpin Single with the third Tpiece, and finally the TSpin Double from the STD in the fourth bag.




Early IPiece
This setup has many dependencies in the first bag and the TSpin Triple is not guaranteed in the second bag in which case it is hard to stack an alternative. Thus this setup is not really useful.


However, if the second bag can be placed like above, then there is a Perfect Clear opportunity after 8 cleared lines. One of the following patterns will work for 64.7 % of all third bags and in any case a TSpin (Single or Double) is made beforehand.



Here are some further ways to get a TSpin Triple in the second bag. None of them offers a Perfect Clear chance (actually the fourth one does but not with a TSpin beforehand).





