From Hard Drop - Tetris Wiki
Super Beta Spin Double (or abbreviated, SBSD) is a double T-Spin Double or sometimes, a T-Spin Double to STSD opener. It is originally created by Wertj. However, there are many variants as the second bag can be tricky when it comes to building on top of the first bag. The setup relies on a late T as the T is what you will hold from the first bag and use the second bag to build the second layer according to the variants. Additionally, the first bag requirements are the same as MKO Stacking, therefore, it is interchangeable with the latter setup. Although the main name of the setup is Super Beta Spin Double, the community often refers to it as Shadow-Blade Spin Double, named after a Reddit poster as the idea of the setup was sparked by him.
First Bag
Both L and J are required before Z and S, respectively.
However, if L comes after Z but before O, it can be assembled like below.
4-line Perfect Clear
You have a 10.71% chance to get a Perfect Clear after 4 lines with these 2 solutions.
ZS variant
The ZS stands for the piece that makes the T-shaped hole in the second bag. In this case, depending on which side is used, the Z or S is used.
Overhang Choices
The T overhang should be used as a last resort because it will require another T piece to stabilize the stack.
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O overhang
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L horizontal overhang
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J horizontal overhang
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I overhang
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T overhang
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L vertical overhang
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J vertical overhang
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Ways to fill in the gap
It is preferable if one can use any of the first three diagrams. The last two diagrams should be used as a last resort because it will require another T piece to stabilize the stack.
6-line Perfect Clear
- J → S → I and Z → L (52.38% PC rate, 2 minimal solutions)
- LJ→I and Z→O / O→J→I and Z→L / O→I→LJ (66.67% PC rate, 4 minimal solutions)
8-line Perfect Clear
All continuations here require a late T piece.
- O → S → L, I (97.70% PC rate, 11 minimal solutions): You can place the Z piece even if you placed O and I first.
All solutions can be found here.
- Z → J → S (91.83% PC rate, 14 minimal solutions)
All solutions can be found here.
ZK variant
The ZK variant is named after Zack101155. He was the one who found this variant while testing the setup in 20TSD mode. In this case. An S/Z piece is added in a unique way to create a new T shaped hole.
Common builds
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LJ
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O (Needs overhang)
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LT
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IJ
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LZ
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6-line Perfect Clear
- L → I (71.43% PC rate, 4 minimal solutions)
8-line Perfect Clear
- O → I → L → Z / L → ZO (96.47% PC rate, 14 minimal solutions)
All solutions can be found here.
- O → I → L → Z / L → ZO + Late J (92.26% PC rate, 15 minimal solutions): The J piece is on hold until the first T-Spin Double is done.
All solves can be found here.
LJ variant
The LJ stands for the piece that makes the T-shaped hole in the second bag. In this case, depending on which side is used, the L or J is used.
Overhang Choices
The T overhang should be used as a last resort because it will require another T piece to stabilize the stack.
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S overhang
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J overhang
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T overhang
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Ways to fill in the gap
It is preferable if one can use one of the first two diagrams. The last three diagrams should be used as a last resort because the shape is unstable.
E2bT variant
In this case, E2bT stands for early second bag T as there is only 1 possible early second bag T situation that is viable which is in the LJ variant. This should only be used as a last resort because it is highly ineffecient.
Main shape
Common builds
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J, L and Z
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O, I and Z
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I, J and Z
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O, J and Z
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O, L and Z
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L, Z, TSS, S
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O, I, TSS, S
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I, J, TSS, S
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J, L, TSS, S
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O, J, TSS, S
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O, L, TSS, S
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- TSS stands for T-Spin Single, so when you make the shape, make a T-Spin Single then add the S (Remember that the opposite always applies when doing the setup from the left side).
Replacing TSD with STSD
If you do not make an overhang beforehand, you can make an STSD on either side of the well.
Alternatively, you can always go for a Perfect Clear. All minimal solutions are shown below, with the first solve covering almost 59% of all bags.
See Also
