Another very descriptive title. This trick is a backwards version of Carry to the opposite elbow. The pattern is a shape distortion of the cascade, the path of only one ball is changed.
Juggle a cascade. Pick one ball & instead of making a cascade throw, toss it straight up on the outside of the pattern to the same height as the rest of the pattern. Throw the next ball as normal then quickly reach over the pattern & Claw the vertical throw at its peak, then carry it back over the pattern in an arc in time to throw the ball back into the cascade pattern. You claw the ball with your palm facing down, as you carry the ball turn your hand over so that the palm is facing upwards at the end. That's it. Be careful not to knock the ball in the air as you carry the ball back.
Now do the same on the other side. Practise making the catch & carry with each hand alternately. Remember that this trick is just a shape distortion of the cascade, so each hand throws alternately & you only throw the next ball when the one before peaks.
Now instead of making a cascade throw after carrying a ball over the top of the pattern, throw it straight up again on the outside of the pattern on the other side. Throw the next ball then reach over, claw the vertical throw & carry it back again. Focus your attention on the ball you claw & carry. Throw it straight up on one side, claw & carry it with the other hand then toss it up on the other side & so on. The other two balls don't alter from the cascade pattern at all.