Triple Double (TD)

Triple doubles are the best way to activate triples in a game

RJ

A TST → TSD setup. A powerful setup to use mid-game. Assuming that you have been maintaining back-to-back, you will send 12 lines, just like DT Cannon.

Building TDs

TDs are mostly built the same way as TSTs are built. The only difference is that you have an empty column underneath at a specific position.

Notch

TDs are most easily recognized and built when you have a block above an empty column.

Using the JL combination is not the only way to create a TD when you see a notch:

Two-step stair

Whenever you see this two-step stair, you can consider building a TST.

Covering with S or Z

The two-step stair can be created by covering a TSD shape with S or Z. The rest is built the same way as you would create a TD from a two-step stair.

Examples:

Using S or Z

When it's a one-step stair, you can use S or Z:

Here's an example using this pattern with some forecasting:

C-Spin

When you use JL to build a TD, it is given a special name of C-Spin. Given its name because of the characteristic C shape that JL forms. You can build TDs this way whenever you recognize a notch that has the same shape as marked as green below.

Note: The Japanese community refers to C-Spin when they say TKI, whereas the western community often refers to this opener when they say TKI.

Examples:

Donation

TDs can also be built after this specific TSS donation that leaves a notch. These are usually done because you can't fill in the required block to make a TSD donation.

Here are some examples:

Opening C-Spin

TKI積み. C-Spin can be used as a TST → TSD or TST opener. The blocks marked sky blue on the second picture below are filled in freestyle.

Holding your O will make it easier for you to fill in the blocks because you'll have more stacking options.

That's it. From here on, stacking is done freestyle. Players often build another TST after the first TST.

Perfect Clear

There are a couple of perfect clear patterns that you can build with your second bag. The chance itself isn't high, but these are nice to be aware of.

Pattern 1 (35.71%)

Pattern 2 (16.67%)

Fixing bad overhangs

TDs are useful when you have a bad overhang, such as below. Note that you can achieve the same effect with an Imperial Cross (third image). However, TDs are often preferred if you have a choice to build either.

Below is not an uncommon situation where you would use I and S to build a TD.

See Also / References

• テトリステンプレ集＠テト譜 on C-Spin

Misc

Skimming to create shapes is not recommended, as it is almost always possible to avoid skimming if you stack correctly. Nevertheless, it is a useful exercise in understanding how the shapes are made. Below are some examples of building TD with skimming: