Double Triple Cannon Setups

Double Triple Cannon, sometimes referred to as DT Cannon or DT, is a T-Spin combo designed by player TKI. The setup is essentially a T-Spin Double followed by a T-Spin Triple. A player utilizes the T-Spin Triple wallkick in SRS to make a T-Spin Double that leads into a T-Spin Triple. In Tetris variants without instant lockdown it is best to hold the soft drop button until the T-Spin Double has been completed. This makes it instantly drop "through the gap" so the T tetromino doesn't rotate early and end up in the wrong spot.

Empty Field Setups
Because so many DT Cannon setups exist, the player can choose a setup that fits the order of their opening bag of pieces. It is usually possible to hold a T through the second bag and into the third, allowing the player to make both T-spins in quick succession.

TKI's Signature

IT Balance

TZ Base Setups

JO Base Setups

IL Base Setups

JL Base Setups

DT-Cannon with no T Pieces

In this setup, the player tries to use no T pieces to set up their DT-Cannon. It is only possible to clear this setup within 14 pieces if the second T is at the end of the second bag, but, if successful, this is the fastest DT-Cannon setup (in terms of piece efficiency, other setups may be faster to execute - see Efficient DT-Cannon Openers section below). Otherwise, the second T will be used for the upstack, reducing this setup's efficiency to the same as the rest listed here.

Other Setups

Efficient DT-Cannon Openers

With the right set of pieces (one of L/J needs to come before S/Z, both if T comes too early) DT-Cannon can be stacked with very few key presses by taking advantage of two-step finesse. Even though a T piece is "wasted" in the stack, this build can be performed faster than many builds that are more piece efficient (such as Albatross or C-Spin), thus making up for the extra pieces placed. In fact, having more pieces in the stack can sometimes be advantageous, because they can more quickly be transitioned into a 4-wide stack or a Tetris stack. Note that the mirror with cannon on the right side uses more key presses, so it should be stacked on the left for optimal efficiency.

Continuations
DT-Cannon is one of the most versatile openers and can be followed up in almost any style of stacking. DT-REN and DT-PC are thought to be some of the best counters to the dreaded 4-Wide opener.

J-spin into T-spin Double

Side 4-Wide (DT-REN)

Tetris stacking

Perfect Clear followup (DT-PC)

There are of course many ways to set up a PC continuation, but this way has a high success rate and is probably the most commonly employed method (as popularized by pro Japanese players like amemiyataiyou100). After the two T-spins, use the five previews to figure out the PC. Some examples:

Higher Notch
Line Clear Shaping

DT Cannon STSD
This setup looks identical to DT Cannon, with the only difference that one further cell is empty at the bottom (marked light grey in the first picture below). It results in a STSD after the first T-Spin Double is cleared. So, it's usually 3 T-Spin Doubles in total.

The DT Cannon STSD has the advantage that no overhang will be left after the last T-Spin. A regular DT cannon has the advantage that it is easier to build, faster to execute and that you can build a 4-wide on top of it. Also, receiving a garbage line with the hole in the wrong column will break the execution of the STSD. As opener, it may be actually better to stack it with an additional line below (see second picture below). The third to fifth picture below show a combined setup that results in 4 T-Spin Doubles.

Similar DT Attack
The S piece takes over the place of the O piece. One must execute the T-Spin Double before the J piece can be placed on the left side. This setup has the disadvantage that it takes more time to soft-drop the T-pieces, that the T-Spin Double can not be held back and that the 2 T-Spins cannot be chained in one combo.

However, one of the first 3 openers shown below will always work for the first bag when the standard DT Cannon openers are not available. Also note that if the first T piece is placed upside down, then those 3 setups result in the exact same stack as that standard DT Cannon where the T piece is placed first (surrounded by S and Z). In the 4th picture you see a SZ Double Triple which doesn't necessarily require to place a T piece in the stack.

Dulse Flame (Darth Flame)
This opener starts with a T-Spin Mini that is used to stack a further line below a DT Cannon (third picture below). That further line allows to clear a further T-Spin Double with the overhang that is left after the execution of the DT Cannon. After the first T-Spin Double is cleared, it resembles a C-Spin (fifth picture below).