Hachispin

Hachispin (or Hachi-Cannon) is an opener created by Hatchispin. The setup consists of a T-Spin Single followed by a T-Spin Triple and Perfect clear.

First 2 bags
The setup needs an early O piece. A T-Spin Single is made at the end of the first bag and a T-Spin Triple at the end of the second bag.

Under circumstances, the second Z piece needs to be soft-dropped. The second L, I and O pieces can be dropped in different ways. If possible, drop the second I piece 2 columns away from the wall because this gives a chance for a Perfect clear.

Perfect Clear continuation
If the second I piece is dropped 2 columns away from the wall, then there is a high chance (69%) to make a Perfect clear (PC) at the end of the third bag (4 further cleared lines) whereas either the third I, L or J piece will stay on hold. The chance is especially high, if T piece comes first in third bag (94%), and also decent if either S, Z or O piece comes first (between 70% and 73%). The PC will always work, if Z and T can be used to fill the bottom rows (see picture 1). Same is true for T and L (see picture 2). More precisely, the PC will always work, if T and either Z or L are received as the first 3 pieces of the 3rd bag except for the starts LIT, ILT, JLT, LJT. It will also always work with TSO (no matter the order), but it will never work with ILJ (no matter the order). Picture 1 shows the most common way to make a PC.

If the second I piece is dropped adjacent to the wall with the L piece above, then there is still a small chance (19%) to make a PC. Again, the chance is the highest if T comes first in third bag (40%). However, all PC opportunities are hard to spot. It is required to clear the third line before placing the Z piece adjacent to the left wall.

If the second I piece is dropped adjacent to the wall but the second L piece is kept on hold until the T-Spin Triple is made, then the chance to make a PC is increased to 74%. Note that this number is a little theoretical though because one can not see or think that many pieces in advance. The 11 most frequent PC opportunities are shown below. Note that the first 3 pictures are similar to the builds where you drop the I piece 2 columns away from the wall (same is true for the pictures in the bottom row). Also interestingly, all these 11 ways can be executed more often than the 4 ways shown above where you dropped the L piece horizontally adjacent to the right wall.

T-Spin continuations
There are easy ways to make either a T-Spin Double or T-Spin Triple in the third bag. It is also possible to prepare an Imperial Cross or a Single Double (SD1).

Examples
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L and J reversed
This setup is similar to Hachispin, but the L and J pieces are placed in the opposite order, which results in  different leftovers. A Perfect Clear after 14 lines is possible if you can stack the 1st to 4th bags like the below diagram.

Here are some solutions. The first is the most common way and may result in a T-Spin Double.

Alternatively, at the second bag, one may assemble like the diagram below which results in a T-Spin Triple. However, it does not have a chance for a PC. TSD is still possible (fourth diagram).

pwn_by_numbers variation
If you get an early L or J piece but no early O piece, then you can still try this variation. It is probably best to place the T piece vertically instead of upside down. With some luck you can fill the right corner with an S piece and make a T-Spin Triple at the end of second bag.

Note that in this variation, it is harder to follow up with a T-Spin Double (T-Spin Triple is still easy). However, if you can stack the second bag like shown above, then there is a very high chance (83%) to make a Perfect clear (PC) at the end of third bag. The chance is especially high (95%), if Z piece comes first in second bag. The chances are also very high (between 88% and 89%), if you receive L or J piece first. The PC will always work, if Z and L can be used to fill the bottom rows (see picture 2). The PC will also always work, if the third bag starts with Z and J piece (see pictures 1 to 4). More precisely, the PC will always work, if Z and either L or J are received as the first 3 pieces of the third bag. It will also always work with TLJ (no matter the order). The first 2 pictures show the most common ways to make a PC.

Another way to make a T-Spin Triple at the end of the second bag is shown below. The right corner is left empty, then covered by an O piece and eventually uncovered by the T-Spin Triple line clear. L piece must stay on hold through second bag.

If you can stack the second bag like shown above (note that the second L piece has not been dropped yet), then there is a 96% to make a Perfect clear. Note that this number is very theoretical though because one can not see or think that many pieces in advance. The 11 most frequent PC opportunities are shown below; there are just too many ways to show them all.