Acid Rain

Acid Rain with the first kick delayed. This timing can be buffered up to 4 frames, making it the best for block punishment.

Acid Rain is one of Lee's best moves. It's an i10 punisher that does 44 damage. The catch is that it's not one, but two just frames. On top of that, because it's a punisher, you need to do something so that the block stun doesn't throw off your tempo.

Unlike b2 loops, the difference between Acid Rain and the alternatives (in particular 1,2,4 and 4,3) is significant. Not only do the easy options do much less damage, they're all minus on hit, whereas Acid Rain gives good oki. So learning Acid Rain is a higher priority than learning b2 loops.

However, like b2 loops, this optimization is still not the highest priority. You should only practise it once you feel confident you want to play Lee.

Input windows

Input	Frame
1	0
3	1–14
3	24–26
3	34–35

The first 3 can be input after the 1 jab's active frame. This delays it, which delays the input windows of the just frames as well.

Common methods

Acid Rain with a filler input to make a stable rhythm

Acid Rain with inputs on frames 0–4–24–34. This is Imyourfather's "boo-doop boop boop".

Acid Rain with inputs on frames 0–10–24–34. With this timing, the first and last intervals are the same.

Acid Rain with inputs on frames 0–10–25–35. With this timing, the second interval is exactly half the other intervals.

As Imyourfather shows, there are two common methods: Adding a filler input ("wa-da-da-da-da"), and doing only the required inputs ("boo-doop boop boop").

The first method uses a simple rhythm with a tempo of 8.5 frames, so notes are on frames 0–8.5–17–25.5–34. For a lot of people this is easiest, since all you have to do is drill that tempo in and bang out the notes.

For the second method, the rhythm is not fixed so there are many variations. These rhythms opt to be less stable to avoid using a filler input. They may also happen to change the tempo, but a 10 frame tempo is no easier than a 8.5 frame one.

Block stun

Punishers depend on the input buffer, which allows you to easily connect e.g., a 10 frame punisher after a -10 move. Without it, you'd need to time the punisher perfectly—too early and you get nothing, too late and they can block.

For the common Acid Rain methods, however, there's a problem. If you've drilled a rhythm for the input, and then you start the rhythm in the input buffer, the just frame windows will be off tempo.

(Transcribe acid-regular-buffer.png and a non-buffered comparison to HTML)

To use Acid Rain as a punisher with these methods, which is its main purpose, not only do you need to time the 3's perfectly, but you need to time the 1 perfectly after the block stun as well. This is a big problem, because different moves have different block stuns, and there's no way you can drill perfect timing for all of them. (That's why the game has an input buffer.)

One potential solution is to visually confirm the input—that is, press the second 3 when you see the first 3 connecting, then use a 10 frame tempo for the third 3.

For this to work, however, you need a fixed input delay. If you only ever play offline, and with the same setup, this might be a viable solution. But even then it's probably not advisable, since visual confirms are a lot harder than rhythms to train to muscle memory for.

Delay method

Acid Rain with inputs on frames 0–14–28–38. Same audio as the top of the page.

If we use the rhythm 0–14–28–38, then it works both with and without an input buffer.

(Transcribe acid-delay-buffer.png and acid-delay.png to HTML)

Why does this work? In the input windows table, frame 0 is not always the frame when you press 1. If the 1 is buffered, frame 0 is pushed forward by however many frames it's buffered.

By delaying 1,3 and thus the just frame windows, we have room to account for frame 0 being pushed forward. For every frame of buffer, we lose a frame of delay, and our just frame windows stay in the same place. This works for up to 4 frames of buffer, since that's the most we can delay 1,3.

Fortunately, this isn't a difficult rhythm either.

Notes

The first "boop" is voiced too early, with a timing of 0–4–21–34. The button presses are on a 0–5–25–35 timing, which still works.