As you get more advanced, I can feed more. Nothing truly 'new' though as there is always a foreshadowing in my earlier materials. The books constantly harp on the daling (inner wrist) point as your target for the extension of energy to the hands and fingers ('Catch' segmennt of the ARC energy path). Of course I'm well aware that the 'lao gong' (center palm) point is much more popular in common teachings as the workhorse for that.
Working with the daling (inner wrist) does not ignore the existence of the laogong. In the end, your entire body including every 'point' becomes totally permeated and suffused with the juice and the radiance. It's just that the daling is vastly more effective as a training target. And the energy it builds at the end of the ARC naturally flows powerfully and seamlessly through your entire hand and beyond to the fingers. Most particularly when the daling concentration is performed in conjunction with the 'soft fist' standing configuration that I call the Da Ling Throttle practice (see all details in book The Aiki Singularity) then - whoa! Nothing better. But It's a training secret to work this way. Most people aren't ready for it. You have to begin with basic relaxation anyway, before delving into any of this more arcane stuff. So please revert to lao gong practice if you are more comfortable that way.
Anyway, today I'm not writing to reiterate all that. Buy the book! Today I want to point out another much more advanced feature - the counterpart point for the ankle/foot. In the foot, we have an analogous situation, in that everybody knows and loves the yongquan point in the front/center of the sole. Yes, that's fine. It's very easy to feel some bubbling energy there. But again, there's a far more powerful energy secret behind the curtain - the 'foot' equivalent to that inner wrist daling point.
For practical purposes, although there is a 'point' at the foot zone concerned, it's best not to even think in terms of dinky little point. The key area for this extremely advanced work is the outer and bottom edge of the rear of your heels. Not too narrow a strip - in fact you can think of almost the entire heel or at least the whole rear half of the heel as the target zone. At some stage, you will understand (through feeling the power blast you practically into the ceiling) that the REBOUND effect is not kidding around. The inner root of the Rebound effect is that rear heel area. Your first awareness of this effect will be the energy suddenly breaking through and surging up at 10X or 100X the normal Rebound power, directly from that specific area. This natural 'overflow' effect is your signal that from then on you can start working it consciously and strengthen it even more.
The very lightest degree of concentration will trigger a surge like you wouldn't believe. But caveat: no use in even thinking about this until, via the lower body drills in book The Aiki Singularity (and the SLO work in all my other stuff) you have, for a long tine, experienced and controlled and intensified huge torrents of regular Rebound energy up from your feet through your legs and upper body in the 'normal' way described in the books. This heel work is a super advanced development. A huge burst of power connects instantaneously from your rear heel to your hands as a kind of SUPER ARC.
Further, just as the daling work does not 'stop' at the inner wrist but rather the daling is a kind of hub or juncture for the outgoing and returning energy on both its sides (forearm on one side, hand on the other), so in a similar way the heel area is a hub that not only discharges the power upward as in the graphic at the top of this post, but also charges the entire foot in 'front' of itself (no arrow for that shown on the graphic). But that's probably too much to go into now, don't want to explode your head entirely.
I did hint at most of the above stuff in my 1st book Juice Radical Taiji Energetics, in the graphic pasted at the head of this blog post, which is direct from the book. But for two reasons, I didn't go into as much detail on it in the original book as I am in this post.
First reason is what I've already said: you won't get anywhere with this until you've gotten way intense results with the earlier stuff, beginning with basic relaxation which leads to the energy experience, control, and intensification. Including the Crack Step outward stream, the Cat Step return surge, the center (double weighted) surge and all the rest. But I do want to set a marker now for those who have eyes to see it.
The other reason I didn't get too deeply into it there is - that was a Tai Chi book. This heel work thing is totally compatible with Tai Chi but the specific teaching on it comes from the Xing Yi (handwritten) manual and it's normally not emphasized in the Tai Chi systems known to me. People do talk about 3 (or more!) 'Nails' and other footwork, especially yongquan point, but that stuff isn't this. That stuff is mostly interpreted physically or else as mere theory and concept, of which few students ever experience the tangible reality.
Possibly most 'normal' Tai Chi teachers are unaware of this due to no personal experience of it. Which is fine because most 'normal' Tai Chi students are nowhere near ready to even think of this. But anyway here it is. Use it wisely.