A Fractal (sometimes also called Spider) is also known as TSD stacking. This is one of the most common T-Spin methods used in multiplayer. Be wary that it can be difficult to build these without using T-blocks in the stack, therefore presenting significant risk in the event that one does not get enough T-blocks in time for the execution. This pattern can be used to make a stack indefinitely high, but setups stacked three or higher are rare.
Japanese people use the term "Double Dagger" (Double Decker) instead of Fractal.
Two or more T-Spin Doubles layered above one another in the following even shape.
Fractal 2 is a similar idea to Fractal 1, however the shape is uneven. Notice that with F2, the hang must be on the correct side to avoid blocking the hole.
An STMB Cave over an incomplete T-Spin Double. This situation is not uncommon after the T-Spin Triple in Triple Double.
Two T-Spin Doubles
By changing the position of the overhang, one can change from fractal to an Imperial Cross.
Zipper is a recursive setup for multiple T-Spin Doubles that involves an advanced skimming technique.
Setup Creation and Execution
The first step is to create a T-Spin Double setup with L and S pieces.
The next step is to use an advanced skimming technique to skim a line with the Z piece. This is a bit tricky.
The third and last step is to place a T piece and then placing an L piece on top to repeat the three steps.
Now repeat the three steps.
Empty Field Setup