Fractal (ダブルダガー)

A TSD → TSD setup. Called "double dagger" in the Japanese community.

Fractals can also have a gap between the two T-Spin shapes:

Building Fractal

Fractals are usually built when you don't anticipate getting a T soon. There are four main ways to create a Fractal.

Building on top of a TSD

Fractals are most often and most easily built on top of an existing TSD.

This pattern of repeating LSJZ is a useful stacking pattern in general and is the basis for LST Stacking, which is essentially building Fractals on top of Fractals.

The above pattern can be built with other pieces:

See LST Stacking where these alternate pieces are more extensively covered. Example:

credit to kazu for the example

LST Stacking

A very practical stacking method that can be used both in versus and Ultra, where you repeat L and S on the left column

STMB Cave

Using STMB Cave and Co. is another a popular way to build a Fractal.

credit to kazu for the third example

STMB Cave can be used over an incomplete TSD to create something called a Fractal Cave:

LT Stacking

LT Stacking is a stacking method where you repeat L on the left side while using the T to do a T-Spin Double. No one uses this stacking method anymore in Ultra, but it is still a useful technique to create Fractals.

The cleanup after doing the two TSDs is tricky, so it's relatively rarely used. Example:

credit to kazu for the example

As a side note, the L will leave a block on the column it was placed, which is useful in several situations:

credit to kazu for the second example. credit to Cold Clear for the third example

JL Prop

This is perhaps the least commonly used technique to build a Fractal because it requires more planning of your pieces. Reminiscent of building DT Cannons. Examples:

credit to kazu for the first and third example. credit to yakine for the second example

This method works well in conjunction with Fractal Cave as a follow-up to build a Fractal.

Just like DT Cannon, other pieces can be used to make the same shape that the L makes.

Tips

A common mistake that people make while building Fractals is building the overhang on the wrong side:

For this example, the resulting field is clean enough to recover with a DT Cannon, however.

Compare Fractal with DT Cannon:

Fractal will be the better option in the majority of cases if there's an extra row underneath.

JZ Stacking

This stacking pattern which utilizes STMB Cave can be used to create shapes similar to Fractal.

credit to kazu for the first example. yakine for the last two examples

Note that repeating IJ makes the same shape:

FOUR