A TSS → TST → PC opener. Created by player hachispin.
There are some downsides: Any misdrop that happens while you're building Hachispin will most likely be fatal. Also, downstacking is not possible until you complete the TST with your second bag.
There are three ways to do the TST from this shape, which covers all possible sequences of minos from the second bag.
If you can do a TST like above, you will have a 69.33% (3494/5040) chance of doing a perfect clear.
You will have a 59.29% chance of making a perfect clear with these two solutions. These are worth memorizing and will always work if you can place a T and Z like the first picture, or if you can put a T and L like the second picture.
Below are the rest of the solutions, and they are harder to spot.
Shown below are the remaining two ways of doing the TST. The second pattern has a low chance (19.21%) of doing a perfect clear, and a perfect clear is not possible for the third pattern. Solutions for the second pattern can be seen here, but they aren't worth memorizing.
Assuming that your opponent plays at the same speed as you play, Hachispin PC is easily countered by many openers because it starts with a TSS. However, it is very easy to continue with a T-Spin after the TST when you cannot follow up with a perfect clear.
Hachispin naturally leads to 7-2 stacking. Here is an example:
Examples on continuing with 6-3 stacking:
Here are some other examples of how you could follow up.
They can be useful depending on the garbage hole that you have below.
Refer to this page for more examples.
Depending on your bag, you can delay doing the TSS and start building your TST for better timing of your attacks.