This technique puts together a well-understood escape from knee on stomach to 50/50 (broken down in some detail in this tutorial), along with a very slick sweep into the well sought out vaporizer finish. As your partner attempts to pass to a knee on stomach position, rotate your hips almost all the way to a north/south position so that your back leg can weave through. From here, your partner drops their left knee to the mat, likely hoping to avoid a sweep and potentially hit a guard pass. Now, you could hit a nice 50/50 heel hook, but instead, you're going to opt for the sweep into the vaporizer. As soon as their knee hits the mat, three things need to happen:

Rotate your hips to your left, so that you can hit the sweep. Hug their knee so that they can't simply step over for a kneebar. Force their left knee to the mat by hipping out to the side, then pushing their foot away.

There's no huge rush once you get to this spot, but you definitely need to focus on keeping them from spinning (by hugging the knee) until you get the lockdown in position (your next step). It's important to control their posture, too, which makes everything else much, much easier. If you can get double underhooks right away, go for it. If not, don't worry - you'll have plenty of time to pummel for them once you've locked the position in place. In any case, you're going to catch a lockdown next, cementing the position in place and preventing any hope of escape. Note that there are two basic ways to pummel your feet into position here, and either will work, depending on your partner's body positioning and your relative leg length.

The first path to finish is simply to duck out the back door, almost like finishing a basic calf slicer from half guard bottom, and attack the foot directly. Using your legs to bring the foot to your hands, you now have three basic finish options:

Calf slicer (very direct, usually has a bit of a pain warning before the submission.) Modified toe hold (like the calf slicer, but with a slight twist, and an outward push with your hips.) Modified heel hook ("steering wheel" finish- by far the nastiest of the three; involves grabbing the heel with one hand and the toes with the other.)

No matter which of the three options you're finishing with, be sure to finish very, very slowly! These submissions, and even the position that leads to them, can be nasty on the knee and ankle of your partner, and even if your partner is an advanced grappler, be sure to take it slowly and even take time to explain what you're doing to them.

The second path to the finish involves sweeping once you get the lockdown and ending up on top, then hitting a ninja roll (which we'll go over below.)